diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 2866f1f23..8dde3c934 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -7,7 +7,7 @@ jobs:
     strategy:
       matrix:
         os: [macOS-latest]
-        node: [8.5.0, 13]
+        node: [8.3.0, 13]
       fail-fast: false
     runs-on: ${{ matrix.os }}
     steps:
diff --git a/index.js b/index.js
deleted file mode 100644
index bead45a87..000000000
--- a/index.js
+++ /dev/null
@@ -1,6 +0,0 @@
-const { zipFunction, zipFunctions } = require('./src/zip')
-
-module.exports = {
-  zipFunction,
-  zipFunctions
-}
diff --git a/package-lock.json b/package-lock.json
index f6675a3ff..118bf8f5a 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -37,6 +37,7 @@
       "version": "7.5.5",
       "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.5.5.tgz",
       "integrity": "sha512-27d4lZoomVyo51VegxI20xZPuSHusqbQag/ztrBC7wegWoQ1nLREPVSKSW8byhTlzTKyNE4ifaTA6lCp7JjpFw==",
+      "dev": true,
       "requires": {
         "@babel/highlight": "^7.0.0"
       }
@@ -414,6 +415,7 @@
       "version": "7.5.0",
       "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.5.0.tgz",
       "integrity": "sha512-7dV4eu9gBxoM0dAnj/BCFDW9LFU0zvTrkq0ugM7pnHEgguOEeOz1so2ZghEdzviYzQEED0r4EAgpsBChKy1TRQ==",
+      "dev": true,
       "requires": {
         "chalk": "^2.0.0",
         "esutils": "^2.0.2",
@@ -1165,11 +1167,6 @@
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       "dev": true
     },
-    "@types/normalize-package-data": {
-      "version": "2.4.0",
-      "resolved": "https://registry.npmjs.org/@types/normalize-package-data/-/normalize-package-data-2.4.0.tgz",
-      "integrity": "sha512-f5j5b/Gf71L+dbqxIpQ4Z2WlmI/mPJ0fOkGGmFgtb6sAu97EPczzbS3/tJKxmcYDj55OX6ssqwDAWOHIYDRDGA=="
-    },
     "@typescript-eslint/typescript-estree": {
       "version": "1.13.0",
       "resolved": "https://registry.npmjs.org/@typescript-eslint/typescript-estree/-/typescript-estree-1.13.0.tgz",
@@ -1201,7 +1198,6 @@
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       "resolved": "https://registry.npmjs.org/aggregate-error/-/aggregate-error-3.0.1.tgz",
       "integrity": "sha512-quoaXsZ9/BLNae5yiNoUz+Nhkwz83GhWwtYFglcjEQB2NDHCIpApbqXxIFnm4Pq/Nvhrsq5sYJFyohrrxnTGAA==",
-      "dev": true,
       "requires": {
         "clean-stack": "^2.0.0",
         "indent-string": "^4.0.0"
@@ -2731,8 +2727,7 @@
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       "resolved": "https://registry.npmjs.org/clean-stack/-/clean-stack-2.2.0.tgz",
-      "integrity": "sha512-4diC9HaTE+KRAMWhDhrGOECgWZxoevMc5TlkObMqNSsVU62PYzXZ/SMTjzyGAFF1YusgxGcSWTEXBhp0CPwQ1A==",
-      "dev": true
+      "integrity": "sha512-4diC9HaTE+KRAMWhDhrGOECgWZxoevMc5TlkObMqNSsVU62PYzXZ/SMTjzyGAFF1YusgxGcSWTEXBhp0CPwQ1A=="
     },
     "clean-yaml-object": {
       "version": "0.1.0",
@@ -2894,8 +2889,7 @@
     "common-path-prefix": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/common-path-prefix/-/common-path-prefix-2.0.0.tgz",
-      "integrity": "sha512-Lb9qbwwyQdRDmyib0qur7BC9/GHIbviTaQebayFsGC/n77AwFhZINCcJkQx2qVv9LJsA8F5ex65F2qrOfWGUyw==",
-      "dev": true
+      "integrity": "sha512-Lb9qbwwyQdRDmyib0qur7BC9/GHIbviTaQebayFsGC/n77AwFhZINCcJkQx2qVv9LJsA8F5ex65F2qrOfWGUyw=="
     },
     "commondir": {
       "version": "1.0.1",
@@ -3064,6 +3058,17 @@
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       "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac="
     },
+    "cp-file": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/cp-file/-/cp-file-7.0.0.tgz",
+      "integrity": "sha512-0Cbj7gyvFVApzpK/uhCtQ/9kE9UnYpxMzaq5nQQC/Dh4iaj5fxp7iEFIullrYwzj8nf0qnsI1Qsx34hAeAebvw==",
+      "requires": {
+        "graceful-fs": "^4.1.2",
+        "make-dir": "^3.0.0",
+        "nested-error-stacks": "^2.0.0",
+        "p-event": "^4.1.0"
+      }
+    },
     "cpy": {
       "version": "7.3.0",
       "resolved": "https://registry.npmjs.org/cpy/-/cpy-7.3.0.tgz",
@@ -3362,7 +3367,6 @@
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       "resolved": "https://registry.npmjs.org/define-properties/-/define-properties-1.1.3.tgz",
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-      "dev": true,
       "requires": {
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       }
@@ -3688,6 +3692,7 @@
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       "resolved": "https://registry.npmjs.org/error-ex/-/error-ex-1.3.2.tgz",
       "integrity": "sha512-7dFHNmqeFSEt2ZBsCriorKnn3Z2pj+fd9kmI6QoWw4//DL+icEBfc0U7qJCisqrTsKTjw4fNFy2pW9OqStD84g==",
+      "dev": true,
       "requires": {
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       }
@@ -3696,7 +3701,6 @@
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-      "dev": true,
       "requires": {
         "es-to-primitive": "^1.2.0",
         "function-bind": "^1.1.1",
@@ -3714,7 +3718,6 @@
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       "resolved": "https://registry.npmjs.org/es-to-primitive/-/es-to-primitive-1.2.0.tgz",
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-      "dev": true,
       "requires": {
         "is-callable": "^1.1.4",
         "is-date-object": "^1.0.1",
@@ -4841,8 +4844,7 @@
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       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/function-bind/-/function-bind-1.1.1.tgz",
-      "integrity": "sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A==",
-      "dev": true
+      "integrity": "sha512-yIovAzMX49sF8Yl58fSCWJ5svSLuaibPxXQJFLmBObTuCr0Mf1KiPopGM9NiFjiYBCbfaa2Fh6breQ6ANVTI0A=="
     },
     "functional-red-black-tree": {
       "version": "1.0.1",
@@ -5290,7 +5292,6 @@
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       "resolved": "https://registry.npmjs.org/has/-/has-1.0.3.tgz",
       "integrity": "sha512-f2dvO0VU6Oej7RkWJGrehjbzMAjFp5/VKPp5tTpWIV4JHHZK1/BxbFRtf/siA2SWTe09caDmVtYYzWEIbBS4zw==",
-      "dev": true,
       "requires": {
         "function-bind": "^1.1.1"
       }
@@ -5320,8 +5321,7 @@
     "has-symbols": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/has-symbols/-/has-symbols-1.0.0.tgz",
-      "integrity": "sha1-uhqPGvKg/DllD1yFA2dwQSIGO0Q=",
-      "dev": true
+      "integrity": "sha1-uhqPGvKg/DllD1yFA2dwQSIGO0Q="
     },
     "has-unicode": {
       "version": "2.0.1",
@@ -5379,7 +5379,8 @@
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       "resolved": "https://registry.npmjs.org/hosted-git-info/-/hosted-git-info-2.8.4.tgz",
-      "integrity": "sha512-pzXIvANXEFrc5oFFXRMkbLPQ2rXRoDERwDLyrcUxGhaZhgP54BBSl9Oheh7Vv0T090cszWBxPjkQQ5Sq1PbBRQ=="
+      "integrity": "sha512-pzXIvANXEFrc5oFFXRMkbLPQ2rXRoDERwDLyrcUxGhaZhgP54BBSl9Oheh7Vv0T090cszWBxPjkQQ5Sq1PbBRQ==",
+      "dev": true
     },
     "http-cache-semantics": {
       "version": "4.0.3",
@@ -5476,14 +5477,6 @@
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       "dev": true
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-    "ignore-walk": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/ignore-walk/-/ignore-walk-3.0.3.tgz",
-      "integrity": "sha512-m7o6xuOaT1aqheYHKf8W6J5pYH85ZI9w077erOzLje3JsB1gkafkAhHHY19dqjulgIZHFm32Cp5uNZgcQqdJKw==",
-      "requires": {
-        "minimatch": "^3.0.4"
-      }
-    },
     "import-fresh": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/import-fresh/-/import-fresh-3.1.0.tgz",
@@ -5527,8 +5520,7 @@
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       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/indent-string/-/indent-string-4.0.0.tgz",
-      "integrity": "sha512-EdDDZu4A2OyIK7Lr/2zG+w5jmbuk1DVBnEwREQvBzspBJkCEbRa8GxU1lghYcaGJCnRWibjDXlq779X1/y5xwg==",
-      "dev": true
+      "integrity": "sha512-EdDDZu4A2OyIK7Lr/2zG+w5jmbuk1DVBnEwREQvBzspBJkCEbRa8GxU1lghYcaGJCnRWibjDXlq779X1/y5xwg=="
     },
     "indexes-of": {
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@@ -5630,7 +5622,8 @@
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       "version": "0.2.1",
       "resolved": "https://registry.npmjs.org/is-arrayish/-/is-arrayish-0.2.1.tgz",
-      "integrity": "sha1-d8mYQFJ6qOyxqLppe4BkWnqSap0="
+      "integrity": "sha1-d8mYQFJ6qOyxqLppe4BkWnqSap0=",
+      "dev": true
     },
     "is-binary-path": {
       "version": "2.1.0",
@@ -5650,8 +5643,7 @@
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       "resolved": "https://registry.npmjs.org/is-callable/-/is-callable-1.1.4.tgz",
-      "integrity": "sha512-r5p9sxJjYnArLjObpjA4xu5EKI3CuKHkJXMhT7kwbpUyIFD1n5PMAsoPvWnvtZiNz7LjkYDRZhd7FlI0eMijEA==",
-      "dev": true
+      "integrity": "sha512-r5p9sxJjYnArLjObpjA4xu5EKI3CuKHkJXMhT7kwbpUyIFD1n5PMAsoPvWnvtZiNz7LjkYDRZhd7FlI0eMijEA=="
     },
     "is-ci": {
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@@ -5685,8 +5677,7 @@
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       "resolved": "https://registry.npmjs.org/is-date-object/-/is-date-object-1.0.1.tgz",
-      "integrity": "sha1-mqIOtq7rv/d/vTPnTKAbM1gdOhY=",
-      "dev": true
+      "integrity": "sha1-mqIOtq7rv/d/vTPnTKAbM1gdOhY="
     },
     "is-descriptor": {
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@@ -5853,7 +5844,6 @@
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       "resolved": "https://registry.npmjs.org/is-regex/-/is-regex-1.0.4.tgz",
       "integrity": "sha1-VRdIm1RwkbCTDglWVM7SXul+lJE=",
-      "dev": true,
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@@ -5874,7 +5864,6 @@
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-      "dev": true,
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@@ -6074,7 +6063,8 @@
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+      "integrity": "sha512-RdJUflcE3cUzKiMqQgsCu06FPu9UdIJO0beYbPhHN4k6apgJtifcoCtT9bcxOpYBtpD2kCM6Sbzg4CausW/PKQ==",
+      "dev": true
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     "js-yaml": {
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@@ -6115,7 +6105,8 @@
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+      "dev": true
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     "json-schema": {
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@@ -6181,9 +6172,9 @@
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+      "version": "6.0.3",
+      "resolved": "https://registry.npmjs.org/kind-of/-/kind-of-6.0.3.tgz",
+      "integrity": "sha512-dcS1ul+9tmeD95T+x28/ehLgd9mENa3LsvDTtzm3vyBEO7RPptvAD+t44WVXaUjTBRcrpFeFlC8WCruUR456hw==",
       "dev": true
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@@ -6234,11 +6225,6 @@
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-      "resolved": "https://registry.npmjs.org/lines-and-columns/-/lines-and-columns-1.1.6.tgz",
-      "integrity": "sha1-HADHQ7QzzQpOgHWPe2SldEDZ/wA="
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@@ -6402,7 +6388,6 @@
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-      "dev": true,
       "requires": {
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@@ -6410,8 +6395,7 @@
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           "resolved": "https://registry.npmjs.org/semver/-/semver-6.3.0.tgz",
-          "integrity": "sha512-b39TBaTSfV6yBrapU89p5fKekE2m/NwnDocOVruQFS1/veMgdzuPcnOM34M6CwxW8jH/lxEa5rBoDeUwu5HHTw==",
-          "dev": true
+          "integrity": "sha512-b39TBaTSfV6yBrapU89p5fKekE2m/NwnDocOVruQFS1/veMgdzuPcnOM34M6CwxW8jH/lxEa5rBoDeUwu5HHTw=="
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@@ -6788,8 +6772,7 @@
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       "resolved": "https://registry.npmjs.org/nested-error-stacks/-/nested-error-stacks-2.1.0.tgz",
-      "integrity": "sha512-AO81vsIO1k1sM4Zrd6Hu7regmJN1NSiAja10gc4bX3F0wd+9rQmcuHQaHVQCYIEC8iFXnE+mavh23GOt7wBgug==",
-      "dev": true
+      "integrity": "sha512-AO81vsIO1k1sM4Zrd6Hu7regmJN1NSiAja10gc4bX3F0wd+9rQmcuHQaHVQCYIEC8iFXnE+mavh23GOt7wBgug=="
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@@ -6832,6 +6815,7 @@
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@@ -6850,20 +6834,6 @@
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-    "npm-bundled": {
-      "version": "1.0.6",
-      "resolved": "https://registry.npmjs.org/npm-bundled/-/npm-bundled-1.0.6.tgz",
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@@ -7095,8 +7065,7 @@
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-      "dev": true
+      "integrity": "sha512-GJzfBZ6DgDAmnuaM3104jR4s1Myxr3Y3zfIyN4z3UdqN69oSRacNK8UhnobDdC+7J2AHCjGwxQubNJfE70SXXQ=="
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     "object-is": {
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@@ -7107,8 +7076,7 @@
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+      "integrity": "sha512-NuAESUOUMrlIXOfHKzD6bpPu3tYt3xvjNdRIQ+FeT0lNb4K8WR70CaDxhuNguS2XG+GjkyMwOzsN5ZktImfhLA=="
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@@ -7135,7 +7103,6 @@
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-      "dev": true,
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@@ -7252,27 +7219,20 @@
       "integrity": "sha1-u+Z0BseaqFxc/sdm/lc0VV36EnQ=",
       "dev": true
     },
-    "p-all": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/p-all/-/p-all-2.1.0.tgz",
-      "integrity": "sha512-HbZxz5FONzz/z2gJfk6bFca0BCiSRF8jU3yCsWOen/vR6lZjfPOu/e7L3uFzTW1i0H8TlC3vqQstEJPQL4/uLA==",
-      "requires": {
-        "p-map": "^2.0.0"
-      },
-      "dependencies": {
-        "p-map": {
-          "version": "2.1.0",
-          "resolved": "https://registry.npmjs.org/p-map/-/p-map-2.1.0.tgz",
-          "integrity": "sha512-y3b8Kpd8OAN444hxfBbFfj1FY/RjtTd8tzYwhUqNYXx0fXx2iX4maP4Qr6qhIKbQXI02wTLAda4fYUbDagTUFw=="
-        }
-      }
-    },
     "p-cancelable": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/p-cancelable/-/p-cancelable-1.1.0.tgz",
       "integrity": "sha512-s73XxOZ4zpt1edZYZzvhqFa6uvQc1vwUa0K0BdtIZgQMAJj9IbebH+JkgKZc9h+B05PKHLOTl4ajG1BmNrVZlw==",
       "dev": true
     },
+    "p-event": {
+      "version": "4.1.0",
+      "resolved": "https://registry.npmjs.org/p-event/-/p-event-4.1.0.tgz",
+      "integrity": "sha512-4vAd06GCsgflX4wHN1JqrMzBh/8QZ4j+rzp0cd2scXRwuBEv+QR3wrVA5aLhWDLw4y2WgDKvzWF3CCLmVM1UgA==",
+      "requires": {
+        "p-timeout": "^2.0.1"
+      }
+    },
     "p-finally": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/p-finally/-/p-finally-2.0.1.tgz",
@@ -7301,6 +7261,29 @@
         "p-limit": "^2.0.0"
       }
     },
+    "p-map": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/p-map/-/p-map-3.0.0.tgz",
+      "integrity": "sha512-d3qXVTF/s+W+CdJ5A29wywV2n8CQQYahlgz2bFiA+4eVNJbHJodPZ+/gXwPGh0bOqA+j8S+6+ckmvLGPk1QpxQ==",
+      "requires": {
+        "aggregate-error": "^3.0.0"
+      }
+    },
+    "p-timeout": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/p-timeout/-/p-timeout-2.0.1.tgz",
+      "integrity": "sha512-88em58dDVB/KzPEx1X0N3LwFfYZPyDc4B6eF38M1rk9VTZMbxXXgjugz8mmwpS9Ox4BDZ+t6t3QP5+/gazweIA==",
+      "requires": {
+        "p-finally": "^1.0.0"
+      },
+      "dependencies": {
+        "p-finally": {
+          "version": "1.0.0",
+          "resolved": "https://registry.npmjs.org/p-finally/-/p-finally-1.0.0.tgz",
+          "integrity": "sha1-P7z7FbiZpEEjs0ttzBi3JDNqLK4="
+        }
+      }
+    },
     "p-try": {
       "version": "2.2.0",
       "resolved": "https://registry.npmjs.org/p-try/-/p-try-2.2.0.tgz",
@@ -7597,7 +7580,6 @@
       "version": "4.2.0",
       "resolved": "https://registry.npmjs.org/pkg-dir/-/pkg-dir-4.2.0.tgz",
       "integrity": "sha512-HRDzbaKjC+AOWVXxAU/x54COGeIv9eb+6CkDSQoNTt4XyWoIJvuPsXizxu/Fr23EiekbtZwmh1IcIG/l/a10GQ==",
-      "dev": true,
       "requires": {
         "find-up": "^4.0.0"
       },
@@ -7606,7 +7588,6 @@
           "version": "4.1.0",
           "resolved": "https://registry.npmjs.org/find-up/-/find-up-4.1.0.tgz",
           "integrity": "sha512-PpOwAdQ/YlXQ2vj8a3h8IipDuYRi3wceVQQGYWxNINccq40Anw7BlsEXCMbt1Zt+OLA6Fq9suIpIWD0OsnISlw==",
-          "dev": true,
           "requires": {
             "locate-path": "^5.0.0",
             "path-exists": "^4.0.0"
@@ -7616,7 +7597,6 @@
           "version": "5.0.0",
           "resolved": "https://registry.npmjs.org/locate-path/-/locate-path-5.0.0.tgz",
           "integrity": "sha512-t7hw9pI+WvuwNJXwk5zVHpyhIqzg2qTlklJOf0mVxGSbe3Fp2VieZcduNYjaLDoy6p9uGpQEGWG87WpMKlNq8g==",
-          "dev": true,
           "requires": {
             "p-locate": "^4.1.0"
           }
@@ -7625,7 +7605,6 @@
           "version": "4.1.0",
           "resolved": "https://registry.npmjs.org/p-locate/-/p-locate-4.1.0.tgz",
           "integrity": "sha512-R79ZZ/0wAxKGu3oYMlz8jy/kbhsNrS7SKZ7PxEHBgJ5+F2mtFW2fK2cOtBh1cHYkQsbzFV7I+EoRKe6Yt0oK7A==",
-          "dev": true,
           "requires": {
             "p-limit": "^2.2.0"
           }
@@ -7857,77 +7836,6 @@
         "path-type": "^3.0.0"
       }
     },
-    "read-pkg-up": {
-      "version": "7.0.0",
-      "resolved": "https://registry.npmjs.org/read-pkg-up/-/read-pkg-up-7.0.0.tgz",
-      "integrity": "sha512-t2ODkS/vTTcRlKwZiZsaLGb5iwfx9Urp924aGzVyboU6+7Z2i6eGr/G1Z4mjvwLLQV3uFOBKobNRGM3ux2PD/w==",
-      "requires": {
-        "find-up": "^4.1.0",
-        "read-pkg": "^5.2.0",
-        "type-fest": "^0.8.1"
-      },
-      "dependencies": {
-        "find-up": {
-          "version": "4.1.0",
-          "resolved": "https://registry.npmjs.org/find-up/-/find-up-4.1.0.tgz",
-          "integrity": "sha512-PpOwAdQ/YlXQ2vj8a3h8IipDuYRi3wceVQQGYWxNINccq40Anw7BlsEXCMbt1Zt+OLA6Fq9suIpIWD0OsnISlw==",
-          "requires": {
-            "locate-path": "^5.0.0",
-            "path-exists": "^4.0.0"
-          }
-        },
-        "locate-path": {
-          "version": "5.0.0",
-          "resolved": "https://registry.npmjs.org/locate-path/-/locate-path-5.0.0.tgz",
-          "integrity": "sha512-t7hw9pI+WvuwNJXwk5zVHpyhIqzg2qTlklJOf0mVxGSbe3Fp2VieZcduNYjaLDoy6p9uGpQEGWG87WpMKlNq8g==",
-          "requires": {
-            "p-locate": "^4.1.0"
-          }
-        },
-        "p-locate": {
-          "version": "4.1.0",
-          "resolved": "https://registry.npmjs.org/p-locate/-/p-locate-4.1.0.tgz",
-          "integrity": "sha512-R79ZZ/0wAxKGu3oYMlz8jy/kbhsNrS7SKZ7PxEHBgJ5+F2mtFW2fK2cOtBh1cHYkQsbzFV7I+EoRKe6Yt0oK7A==",
-          "requires": {
-            "p-limit": "^2.2.0"
-          }
-        },
-        "parse-json": {
-          "version": "5.0.0",
-          "resolved": "https://registry.npmjs.org/parse-json/-/parse-json-5.0.0.tgz",
-          "integrity": "sha512-OOY5b7PAEFV0E2Fir1KOkxchnZNCdowAJgQ5NuxjpBKTRP3pQhwkrkxqQjeoKJ+fO7bCpmIZaogI4eZGDMEGOw==",
-          "requires": {
-            "@babel/code-frame": "^7.0.0",
-            "error-ex": "^1.3.1",
-            "json-parse-better-errors": "^1.0.1",
-            "lines-and-columns": "^1.1.6"
-          }
-        },
-        "read-pkg": {
-          "version": "5.2.0",
-          "resolved": "https://registry.npmjs.org/read-pkg/-/read-pkg-5.2.0.tgz",
-          "integrity": "sha512-Ug69mNOpfvKDAc2Q8DRpMjjzdtrnv9HcSMX+4VsZxD1aZ6ZzrIE7rlzXBtWTyhULSMKg076AW6WR5iZpD0JiOg==",
-          "requires": {
-            "@types/normalize-package-data": "^2.4.0",
-            "normalize-package-data": "^2.5.0",
-            "parse-json": "^5.0.0",
-            "type-fest": "^0.6.0"
-          },
-          "dependencies": {
-            "type-fest": {
-              "version": "0.6.0",
-              "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.6.0.tgz",
-              "integrity": "sha512-q+MB8nYR1KDLrgr4G5yemftpMC7/QLqVndBmEEdqzmNj5dcFOO4Oo8qlwZE3ULT3+Zim1F8Kq4cBnikNhlCMlg=="
-            }
-          }
-        },
-        "type-fest": {
-          "version": "0.8.1",
-          "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.8.1.tgz",
-          "integrity": "sha512-4dbzIzqvjtgiM5rw1k5rEHtBANKmdudhGyBEajN01fEyhaAIhsoKNy6y7+IN93IfpFtwY9iqi7kD+xwKhQsNJA=="
-        }
-      }
-    },
     "readable-stream": {
       "version": "3.4.0",
       "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-3.4.0.tgz",
@@ -8563,6 +8471,7 @@
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/spdx-correct/-/spdx-correct-3.1.0.tgz",
       "integrity": "sha512-lr2EZCctC2BNR7j7WzJ2FpDznxky1sjfxvvYEyzxNyb6lZXHODmEoJeFu4JupYlkfha1KZpJyoqiJ7pgA1qq8Q==",
+      "dev": true,
       "requires": {
         "spdx-expression-parse": "^3.0.0",
         "spdx-license-ids": "^3.0.0"
@@ -8571,12 +8480,14 @@
     "spdx-exceptions": {
       "version": "2.2.0",
       "resolved": "https://registry.npmjs.org/spdx-exceptions/-/spdx-exceptions-2.2.0.tgz",
-      "integrity": "sha512-2XQACfElKi9SlVb1CYadKDXvoajPgBVPn/gOQLrTvHdElaVhr7ZEbqJaRnJLVNeaI4cMEAgVCeBMKF6MWRDCRA=="
+      "integrity": "sha512-2XQACfElKi9SlVb1CYadKDXvoajPgBVPn/gOQLrTvHdElaVhr7ZEbqJaRnJLVNeaI4cMEAgVCeBMKF6MWRDCRA==",
+      "dev": true
     },
     "spdx-expression-parse": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/spdx-expression-parse/-/spdx-expression-parse-3.0.0.tgz",
       "integrity": "sha512-Yg6D3XpRD4kkOmTpdgbUiEJFKghJH03fiC1OPll5h/0sO6neh2jqRDVHOQ4o/LMea0tgCkbMgea5ip/e+MkWyg==",
+      "dev": true,
       "requires": {
         "spdx-exceptions": "^2.1.0",
         "spdx-license-ids": "^3.0.0"
@@ -8585,7 +8496,8 @@
     "spdx-license-ids": {
       "version": "3.0.5",
       "resolved": "https://registry.npmjs.org/spdx-license-ids/-/spdx-license-ids-3.0.5.tgz",
-      "integrity": "sha512-J+FWzZoynJEXGphVIS+XEh3kFSjZX/1i9gFBaWQcB+/tmpe2qUsSBABpcxqxnAxFdiUFEgAX1bjYGQvIZmoz9Q=="
+      "integrity": "sha512-J+FWzZoynJEXGphVIS+XEh3kFSjZX/1i9gFBaWQcB+/tmpe2qUsSBABpcxqxnAxFdiUFEgAX1bjYGQvIZmoz9Q==",
+      "dev": true
     },
     "speedometer": {
       "version": "1.0.0",
@@ -8714,7 +8626,6 @@
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/string.prototype.trimleft/-/string.prototype.trimleft-2.1.0.tgz",
       "integrity": "sha512-FJ6b7EgdKxxbDxc79cOlok6Afd++TTs5szo+zJTUyow3ycrRfJVE2pq3vcN53XexvKZu/DJMDfeI/qMiZTrjTw==",
-      "dev": true,
       "requires": {
         "define-properties": "^1.1.3",
         "function-bind": "^1.1.1"
@@ -8724,7 +8635,6 @@
       "version": "2.1.0",
       "resolved": "https://registry.npmjs.org/string.prototype.trimright/-/string.prototype.trimright-2.1.0.tgz",
       "integrity": "sha512-fXZTSV55dNBwv16uw+hh5jkghxSnc5oHq+5K/gXgizHwAvMetdAJlHqqoFC1FSDVPYWLkAKl2cxpUT41sV7nSg==",
-      "dev": true,
       "requires": {
         "define-properties": "^1.1.3",
         "function-bind": "^1.1.1"
@@ -9394,7 +9304,6 @@
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/util.promisify/-/util.promisify-1.0.0.tgz",
       "integrity": "sha512-i+6qA2MPhvoKLuxnJNpXAGhg7HphQOSUq2LKMZD0m15EiskXUkMvKdF4Uui0WYeCUGea+o2cw/ZuwehtfsrNkA==",
-      "dev": true,
       "requires": {
         "define-properties": "^1.1.2",
         "object.getownpropertydescriptors": "^2.0.3"
@@ -9416,6 +9325,7 @@
       "version": "3.0.4",
       "resolved": "https://registry.npmjs.org/validate-npm-package-license/-/validate-npm-package-license-3.0.4.tgz",
       "integrity": "sha512-DpKm2Ui/xN7/HQKCtpZxoRWBhZ9Z0kqtygG8XCgNQ8ZlDnxuQmWhj566j8fN4Cu3/JmbhsDo7fcAJq4s9h27Ew==",
+      "dev": true,
       "requires": {
         "spdx-correct": "^3.0.0",
         "spdx-expression-parse": "^3.0.0"
diff --git a/package.json b/package.json
index a4206efc3..874593086 100644
--- a/package.json
+++ b/package.json
@@ -24,15 +24,19 @@
   },
   "dependencies": {
     "archiver": "^3.0.0",
-    "debug": "^4.1.1",
+    "common-path-prefix": "^2.0.0",
+    "cp-file": "^7.0.0",
     "elf-tools": "^1.1.1",
+    "end-of-stream": "^1.4.1",
     "glob": "^7.1.3",
-    "npm-packlist": "^1.1.12",
-    "p-all": "^2.0.0",
+    "make-dir": "^3.0.0",
+    "p-map": "^3.0.0",
+    "path-exists": "^4.0.0",
+    "pkg-dir": "^4.2.0",
     "precinct": "^6.1.1",
-    "read-pkg-up": "^7.0.0",
     "require-package-name": "^2.0.1",
     "resolve": "^1.10.0",
+    "util.promisify": "^1.0.0",
     "yargs": "^14.2.0"
   },
   "devDependencies": {
@@ -62,11 +66,10 @@
     "pkg": "^4.3.7",
     "prettier": "^1.16.4",
     "rimraf": "^3.0.0",
-    "tmp-promise": "^2.0.2",
-    "util.promisify": "^1.0.0"
+    "tmp-promise": "^2.0.2"
   },
   "engines": {
-    "node": ">=8.5.0"
+    "node": ">=8.3.0"
   },
   "homepage": "https://github.com/netlify/zip-it-and-ship-it#README",
   "keywords": [
@@ -79,7 +82,7 @@
     "static"
   ],
   "license": "MIT",
-  "main": "index.js",
+  "main": "src/main.js",
   "pkg": {
     "targets": [
       "node10"
@@ -93,7 +96,7 @@
     "prepublishOnly": "run-s pkg && git push && git push --tags && gh-release -a build/zip-it-and-ship-it_$(git describe --abbrev=0 --tags)_Linux-64bit.tar.gz,build/zip-it-and-ship-it_$(git describe --abbrev=0 --tags)_macOS-64bit.tar.gz",
     "test": "run-s test:* test:dev:*",
     "test-ci": "run-s test:* test:ci:*",
-    "test:lint": "eslint --ignore-path .gitignore --fix --cache --format=codeframe --max-warnings=0 \"src/**/*.js\" \"*.js\"",
+    "test:lint": "eslint --ignore-path .gitignore --fix --cache --format=codeframe --max-warnings=0 \"src/**/*.js\"",
     "test:prettier": "prettier --ignore-path .gitignore --write --loglevel warn \"src/**/*.js\" \"*.{js,md,yml,json}\"",
     "test:dev:ava": "ava",
     "test:ci:ava": "nyc -r lcovonly -r text -r json ava",
diff --git a/src/archive.js b/src/archive.js
new file mode 100644
index 000000000..4dd44d90e
--- /dev/null
+++ b/src/archive.js
@@ -0,0 +1,34 @@
+const { createWriteStream } = require('fs')
+
+const archiver = require('archiver')
+const endOfStream = require('end-of-stream')
+const promisify = require('util.promisify')
+
+const pEndOfStream = promisify(endOfStream)
+
+// Start zipping files
+const startZip = function(destPath) {
+  const output = createWriteStream(destPath)
+  const archive = archiver('zip', { level: 9 })
+  archive.pipe(output)
+  return { archive, output }
+}
+
+// Add new file to zip
+const addZipFile = function(archive, file, name, stat) {
+  // Ensure sha256 stability regardless of mtime
+  archive.file(file, { name, mode: stat.mode, date: new Date(0), stats: stat })
+}
+
+// Add new file content to zip
+const addZipContent = function(archive, content, name) {
+  archive.append(content, { name, date: new Date(0) })
+}
+
+// End zipping files
+const endZip = async function(archive, output) {
+  archive.finalize()
+  await pEndOfStream(output)
+}
+
+module.exports = { startZip, addZipFile, addZipContent, endZip }
diff --git a/src/bin.test.js b/src/bin.test.js
index 2f5f4c214..232d344e2 100644
--- a/src/bin.test.js
+++ b/src/bin.test.js
@@ -22,7 +22,7 @@ test('CLI | --help', async t => {
   t.true(stdout.includes('Options:'))
 })
 
-test.skip('CLI | Normal execution', async t => {
+test('CLI | Normal execution', async t => {
   const tmpDir = await tmpName({ prefix: 'zip-it-test' })
   const { stdout } = await execa.command(`${BINARY_PATH} ${join(FIXTURES_DIR, 'simple')} ${tmpDir}`)
   const zipped = JSON.parse(stdout)
diff --git a/src/dependencies.js b/src/dependencies.js
new file mode 100644
index 000000000..d980d65f6
--- /dev/null
+++ b/src/dependencies.js
@@ -0,0 +1,213 @@
+const { dirname } = require('path')
+
+const precinct = require('precinct')
+const resolve = require('resolve')
+const requirePackageName = require('require-package-name')
+const promisify = require('util.promisify')
+const glob = require('glob')
+
+const pResolve = promisify(resolve)
+const pGlob = promisify(glob)
+
+// Retrieve all the files recursively required by a Node.js file
+const getDependencies = async function(handler, packageRoot) {
+  const packageJson = getPackageJson(packageRoot)
+
+  const state = { localFiles: [], modulePaths: [] }
+
+  try {
+    return await getFileDependencies(handler, packageJson, state)
+  } catch (error) {
+    error.message = `In file "${handler}": ${error.message}`
+    throw error
+  }
+}
+
+const getPackageJson = function(packageRoot) {
+  if (packageRoot === undefined) {
+    return {}
+  }
+
+  return require(`${packageRoot}/package.json`)
+}
+
+const getFileDependencies = async function(path, packageJson, state) {
+  if (state.localFiles.includes(path)) {
+    return []
+  }
+
+  state.localFiles.push(path)
+
+  const basedir = dirname(path)
+  // This parses JavaScript in `path` to retrieve all the `require()` statements
+  // TODO: `precinct.paperwork()` uses `fs.readFileSync()` under the hood,
+  // but should use `fs.readFile()` instead
+  const dependencies = precinct.paperwork(path, { includeCore: false })
+
+  const depsPaths = await Promise.all(
+    dependencies.map(dependency => getImportDependencies(dependency, basedir, packageJson, state))
+  )
+  return [].concat(...depsPaths)
+}
+
+// `require()` statements can be either `require('moduleName')` or
+// `require(path)`
+const getImportDependencies = function(dependency, basedir, packageJson, state) {
+  if (LOCAL_IMPORT_REGEXP.test(dependency)) {
+    return getLocalImportDependencies(dependency, basedir, packageJson, state)
+  }
+
+  return getModuleDependencies(dependency, basedir, state, packageJson)
+}
+
+const LOCAL_IMPORT_REGEXP = /^(\.|\/)/
+
+// When a file requires another one, we apply the top-level logic recursively
+const getLocalImportDependencies = async function(dependency, basedir, packageJson, state) {
+  const dependencyPath = await pResolve(dependency, { basedir })
+  const depsPath = await getFileDependencies(dependencyPath, packageJson, state)
+  return [dependencyPath, ...depsPath]
+}
+
+// When a file requires a module, we find its path inside `node_modules` and
+// use all its published files. We also recurse on the module's dependencies.
+const getModuleDependencies = async function(dependency, basedir, state, packageJson) {
+  const moduleName = requirePackageName(dependency.replace(BACKSLASH_REGEXP, '/'))
+
+  try {
+    return await getModuleNameDependencies(moduleName, basedir, state)
+  } catch (error) {
+    return handleModuleNotFound({ error, moduleName, packageJson })
+  }
+}
+
+const BACKSLASH_REGEXP = /\\/g
+
+const getModuleNameDependencies = async function(moduleName, basedir, state) {
+  if (EXCLUDED_MODULES.includes(moduleName)) {
+    return []
+  }
+
+  // Find the Node.js module directory path
+  const packagePath = await pResolve(`${moduleName}/package.json`, { basedir })
+  const modulePath = dirname(packagePath)
+
+  if (state.modulePaths.includes(modulePath)) {
+    return []
+  }
+
+  state.modulePaths.push(modulePath)
+
+  const pkg = require(packagePath)
+
+  const [publishedFiles, depsPaths] = await Promise.all([
+    getPublishedFiles(modulePath),
+    getNestedModules(modulePath, state, pkg)
+  ])
+  return [...publishedFiles, ...depsPaths]
+}
+
+const EXCLUDED_MODULES = ['aws-sdk']
+
+// We use all the files published by the Node.js except some that are not needed
+const getPublishedFiles = async function(modulePath) {
+  const ignore = getIgnoredFiles(modulePath)
+  const publishedFiles = await pGlob(`${modulePath}/**`, {
+    ignore,
+    nodir: true,
+    absolute: true,
+    dot: true
+  })
+  return publishedFiles
+}
+
+const getIgnoredFiles = function(modulePath) {
+  return IGNORED_FILES.map(ignoreFile => `${modulePath}/${ignoreFile}`)
+}
+
+// To make the zip archive smaller, we remove those.
+const IGNORED_FILES = [
+  'node_modules/**',
+  '.npmignore',
+  'package-lock.json',
+  'yarn.lock',
+  '*.log',
+  '*.lock',
+  '*~',
+  '*.map',
+  '*.ts',
+  '*.patch'
+]
+
+// Apply the Node.js module logic recursively on its own dependencies, using
+// the `package.json` `dependencies`, `peerDependencies` and
+// `optionalDependencies` keys
+const getNestedModules = async function(modulePath, state, pkg) {
+  const dependencies = getNestedDependencies(pkg)
+
+  const depsPaths = await Promise.all(
+    dependencies.map(dependency => getModuleDependencies(dependency, modulePath, state, pkg))
+  )
+  return [].concat(...depsPaths)
+}
+
+const getNestedDependencies = function({ dependencies = {}, peerDependencies = {}, optionalDependencies = {} }) {
+  return [
+    ...Object.keys(dependencies),
+    ...Object.keys(peerDependencies).filter(shouldIncludePeerDependency),
+    ...Object.keys(optionalDependencies)
+  ]
+}
+
+// Workaround for https://github.com/netlify/zip-it-and-ship-it/issues/73
+// TODO: remove this after adding proper modules exclusion as outlined in
+// https://github.com/netlify/zip-it-and-ship-it/issues/68
+const shouldIncludePeerDependency = function(name) {
+  return !EXCLUDED_PEER_DEPENDENCIES.includes(name)
+}
+
+const EXCLUDED_PEER_DEPENDENCIES = ['prisma2']
+
+// Modules can be required conditionally (inside an `if` or `try`/`catch` block).
+// When a `require()` statement is found but the module is not found, it is
+// possible that that block either always evaluates to:
+//  - `false`: in which case, we should not bundle the dependency
+//  - `true`: in which case, we should report the dependency as missing
+// Those conditional modules might be:
+//  - present in the `package.json` `dependencies`
+//  - present in the `package.json` `optionalDependencies`
+//  - present in the `package.json` `peerDependencies`
+//  - not present in the `package.json`, if the module author wants its users
+//    to explicitly install it as an optional dependency.
+// The current implementation:
+//  - when parsing `require()` statements inside function files, always consider
+//    conditional modules to be included, i.e. report them if not found.
+//    This is because our current parsing logic does not know whether a
+//    `require()` is conditional or not.
+//  - when parsing module dependencies, ignore `require()` statements if not
+//    present in the `package.json` `*dependencies`. I.e. user must manually
+//    install them if the module is used.
+// `optionalDependencies`:
+//  - are not reported when missing
+//  - are included in module dependencies
+const handleModuleNotFound = function({ error, moduleName, packageJson }) {
+  if (error.code === 'MODULE_NOT_FOUND' && isOptionalModule(moduleName, packageJson)) {
+    return []
+  }
+
+  throw error
+}
+
+const isOptionalModule = function(
+  moduleName,
+  { optionalDependencies = {}, peerDependenciesMeta = {}, peerDependencies = {} }
+) {
+  return (
+    optionalDependencies[moduleName] !== undefined ||
+    (peerDependenciesMeta[moduleName] &&
+      peerDependenciesMeta[moduleName].optional &&
+      peerDependencies[moduleName] !== undefined)
+  )
+}
+
+module.exports = { getDependencies }
diff --git a/src/finders.js b/src/finders.js
deleted file mode 100644
index 619bc3c22..000000000
--- a/src/finders.js
+++ /dev/null
@@ -1,195 +0,0 @@
-const path = require('path')
-const fs = require('fs')
-
-const packList = require('npm-packlist')
-const precinct = require('precinct')
-const resolve = require('resolve')
-const readPkgUp = require('read-pkg-up')
-const requirePackageName = require('require-package-name')
-const alwaysIgnored = new Set(['aws-sdk'])
-const debug = require('debug')('@netlify/zip-it-and-ship-it:finders')
-
-const ignoredExtensions = new Set([
-  '.log',
-  '.lock',
-  '.html',
-  '.md',
-  '.map',
-  '.ts',
-  '.png',
-  '.jpeg',
-  '.jpg',
-  '.gif',
-  '.css',
-  '.patch'
-])
-
-function ignoreMissing(dependency, optional) {
-  return alwaysIgnored.has(dependency) || (optional && dependency in optional)
-}
-
-function includeModuleFile(packageJson, moduleFilePath) {
-  if (packageJson.files) {
-    return true
-  }
-
-  return !ignoredExtensions.has(path.extname(moduleFilePath))
-}
-
-function getDependencies(filename, basedir) {
-  const servicePath = basedir
-
-  const filePaths = new Set()
-  const modulePaths = new Set()
-  const pkgs = {}
-
-  const modulesToProcess = []
-  const localFilesToProcess = [filename]
-
-  function handle(name, basedir, optionalDependencies) {
-    const moduleName = requirePackageName(name.replace(/\\/, '/'))
-
-    if (alwaysIgnored.has(moduleName)) {
-      return
-    }
-
-    try {
-      const pathToModule = resolve.sync(path.join(moduleName, 'package.json'), {
-        basedir
-      })
-      const pkg = readPkgUp.sync({ cwd: pathToModule })
-
-      if (pkg) {
-        modulesToProcess.push(pkg)
-      }
-    } catch (e) {
-      if (e.code === 'MODULE_NOT_FOUND') {
-        if (ignoreMissing(moduleName, optionalDependencies)) {
-          debug(`WARNING missing optional dependency: ${moduleName}`)
-          return null
-        }
-        try {
-          // this resolves the requested import also against any set up NODE_PATH extensions, etc.
-          const resolved = require.resolve(name)
-          localFilesToProcess.push(resolved)
-          return
-        } catch (e) {
-          if (moduleName === 'encoding') {
-            // node-fetch has an undeclared peer dependency on encoding
-            // We add an exception for this one module because it is very popular and people complain about it
-            debug(`WARNING missing optional dependency: ${moduleName}`)
-          } else {
-            throw new Error(`Could not find "${moduleName}" module in file: ${filename.replace(
-              path.dirname(basedir),
-              ''
-            )}.
-
-  Please ensure "${moduleName}" is installed in the project.`)
-          }
-        }
-      }
-      throw e
-    }
-  }
-
-  while (localFilesToProcess.length) {
-    const currentLocalFile = localFilesToProcess.pop()
-
-    if (filePaths.has(currentLocalFile)) {
-      continue
-    }
-
-    filePaths.add(currentLocalFile)
-    precinct.paperwork(currentLocalFile, { includeCore: false }).forEach(dependency => {
-      if (dependency.indexOf('.') === 0) {
-        const abs = resolve.sync(dependency, {
-          basedir: path.dirname(currentLocalFile)
-        })
-        localFilesToProcess.push(abs)
-      } else {
-        handle(dependency, servicePath)
-      }
-    })
-  }
-
-  while (modulesToProcess.length) {
-    const currentModule = modulesToProcess.pop()
-    const currentModulePath = path.join(currentModule.path, '..')
-    const packageJson = currentModule.packageJson
-
-    if (packageJson.peerDependenciesMeta) {
-      packageJson.optionalDependencies = packageJson.optionalDependencies || {}
-
-      for (const depKey in packageJson.peerDependenciesMeta) {
-        if (packageJson.peerDependenciesMeta[depKey].optional) {
-          packageJson.optionalDependencies[depKey] = packageJson.peerDependencies[depKey]
-        }
-      }
-    }
-
-    if (modulePaths.has(currentModulePath)) {
-      continue
-    }
-    modulePaths.add(currentModulePath)
-    pkgs[currentModulePath] = packageJson
-    ;['dependencies', 'peerDependencies', 'optionalDependencies'].forEach(key => {
-      const dependencies = packageJson[key]
-
-      if (dependencies) {
-        Object.keys(dependencies).forEach(dependency => {
-          handle(dependency, currentModulePath, packageJson.optionalDependencies)
-        })
-      }
-    })
-  }
-
-  modulePaths.forEach(modulePath => {
-    const packageJson = pkgs[modulePath]
-    let moduleFilePaths
-
-    moduleFilePaths = packList.sync({ path: modulePath })
-
-    moduleFilePaths.forEach(moduleFilePath => {
-      if (includeModuleFile(packageJson, moduleFilePath)) {
-        filePaths.add(path.join(modulePath, moduleFilePath))
-      }
-    })
-  })
-
-  // TODO: get rid of this
-  const sizes = {}
-  filePaths.forEach(filepath => {
-    const stat = fs.lstatSync(filepath)
-    const ext = path.extname(filepath)
-    sizes[ext] = (sizes[ext] || 0) + stat.size
-  })
-  debug('Sizes per extension: ', sizes)
-
-  return Array.from(filePaths)
-}
-
-function findModuleDir(dir) {
-  let basedir = dir
-  while (!fs.existsSync(path.join(basedir, 'package.json'))) {
-    const newBasedir = path.dirname(basedir)
-    if (newBasedir === basedir) {
-      return null
-    }
-    basedir = newBasedir
-  }
-  return basedir
-}
-
-function findHandler(functionPath) {
-  if (fs.lstatSync(functionPath).isFile()) {
-    return functionPath
-  }
-
-  const handlerPath = path.join(functionPath, `${path.basename(functionPath)}.js`)
-  if (!fs.existsSync(handlerPath)) {
-    return
-  }
-  return handlerPath
-}
-
-module.exports = { getDependencies, findModuleDir, findHandler }
diff --git a/src/fixtures/node-module-deep-conditional/function.js b/src/fixtures/node-module-deep-conditional/function.js
new file mode 100644
index 000000000..b15ec8ed6
--- /dev/null
+++ b/src/fixtures/node-module-deep-conditional/function.js
@@ -0,0 +1,3 @@
+require('test')
+
+module.exports = true
diff --git a/src/fixtures/node-module-deep-conditional/node_modules/test/index.js b/src/fixtures/node-module-deep-conditional/node_modules/test/index.js
new file mode 100644
index 000000000..676ccac83
--- /dev/null
+++ b/src/fixtures/node-module-deep-conditional/node_modules/test/index.js
@@ -0,0 +1,3 @@
+try {
+  require('conditional-dep')
+} catch (error) {}
diff --git a/src/fixtures/node-module-deep-conditional/node_modules/test/package.json b/src/fixtures/node-module-deep-conditional/node_modules/test/package.json
new file mode 100644
index 000000000..0967ef424
--- /dev/null
+++ b/src/fixtures/node-module-deep-conditional/node_modules/test/package.json
@@ -0,0 +1 @@
+{}
diff --git a/src/fixtures/node-module-deep-conditional/package.json b/src/fixtures/node-module-deep-conditional/package.json
new file mode 100644
index 000000000..57c3fd90b
--- /dev/null
+++ b/src/fixtures/node-module-deep-conditional/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "test": "0.0.1"
+  }
+}
diff --git a/src/fixtures/node-module-included/function.js b/src/fixtures/node-module-included/function.js
new file mode 100644
index 000000000..28b1bd444
--- /dev/null
+++ b/src/fixtures/node-module-included/function.js
@@ -0,0 +1 @@
+module.exports = require('test')
diff --git a/src/fixtures/node-module-included/node_modules/test/index.js b/src/fixtures/node-module-included/node_modules/test/index.js
new file mode 100644
index 000000000..33c1891f8
--- /dev/null
+++ b/src/fixtures/node-module-included/node_modules/test/index.js
@@ -0,0 +1 @@
+module.exports = true
diff --git a/src/fixtures/node-module-included/node_modules/test/package.json b/src/fixtures/node-module-included/node_modules/test/package.json
new file mode 100644
index 000000000..0967ef424
--- /dev/null
+++ b/src/fixtures/node-module-included/node_modules/test/package.json
@@ -0,0 +1 @@
+{}
diff --git a/src/fixtures/node-module-included/node_modules/test/test.html b/src/fixtures/node-module-included/node_modules/test/test.html
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/fixtures/node-module-included/node_modules/test/test.map b/src/fixtures/node-module-included/node_modules/test/test.map
new file mode 100644
index 000000000..e69de29bb
diff --git a/src/fixtures/node-module-included/package.json b/src/fixtures/node-module-included/package.json
new file mode 100644
index 000000000..5416bb918
--- /dev/null
+++ b/src/fixtures/node-module-included/package.json
@@ -0,0 +1,7 @@
+{
+  "name": "local-node-module",
+  "version": "1.0.0",
+  "dependencies": {
+    "test": "1.0.2"
+  }
+}
diff --git a/src/fixtures/node-module-optional-whitelist/function.js b/src/fixtures/node-module-missing-conditional/function.js
similarity index 100%
rename from src/fixtures/node-module-optional-whitelist/function.js
rename to src/fixtures/node-module-missing-conditional/function.js
diff --git a/src/fixtures/node-module-missing-deep/function.js b/src/fixtures/node-module-missing-deep/function.js
new file mode 100644
index 000000000..b15ec8ed6
--- /dev/null
+++ b/src/fixtures/node-module-missing-deep/function.js
@@ -0,0 +1,3 @@
+require('test')
+
+module.exports = true
diff --git a/src/fixtures/node-module-missing-deep/node_modules/test/index.js b/src/fixtures/node-module-missing-deep/node_modules/test/index.js
new file mode 100644
index 000000000..b803e7c91
--- /dev/null
+++ b/src/fixtures/node-module-missing-deep/node_modules/test/index.js
@@ -0,0 +1 @@
+require('missing-dep')
diff --git a/src/fixtures/node-module-missing-deep/node_modules/test/package.json b/src/fixtures/node-module-missing-deep/node_modules/test/package.json
new file mode 100644
index 000000000..0967ef424
--- /dev/null
+++ b/src/fixtures/node-module-missing-deep/node_modules/test/package.json
@@ -0,0 +1 @@
+{}
diff --git a/src/fixtures/node-module-missing-deep/package.json b/src/fixtures/node-module-missing-deep/package.json
new file mode 100644
index 000000000..57c3fd90b
--- /dev/null
+++ b/src/fixtures/node-module-missing-deep/package.json
@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "test": "0.0.1"
+  }
+}
diff --git a/src/fixtures/node-module-optional/function.js b/src/fixtures/node-module-missing-optional/function.js
similarity index 100%
rename from src/fixtures/node-module-optional/function.js
rename to src/fixtures/node-module-missing-optional/function.js
diff --git a/src/fixtures/node-module-optional/package.json b/src/fixtures/node-module-missing-optional/package.json
similarity index 100%
rename from src/fixtures/node-module-optional/package.json
rename to src/fixtures/node-module-missing-optional/package.json
diff --git a/src/fixtures/node-module-peer-not-optional/function.js b/src/fixtures/node-module-peer-not-optional/function.js
new file mode 100644
index 000000000..4295c0e6e
--- /dev/null
+++ b/src/fixtures/node-module-peer-not-optional/function.js
@@ -0,0 +1,7 @@
+try {
+  // eslint-disable-next-line node/no-missing-require
+  require('consistent-ids')
+  // eslint-disable-next-line no-empty
+} catch (error) {}
+
+module.exports = true
diff --git a/src/fixtures/node-module-peer-not-optional/package.json b/src/fixtures/node-module-peer-not-optional/package.json
new file mode 100644
index 000000000..2de56ba39
--- /dev/null
+++ b/src/fixtures/node-module-peer-not-optional/package.json
@@ -0,0 +1,10 @@
+{
+  "peerDependencies": {
+    "consistent-ids": "0.1.1"
+  },
+  "peerDependenciesMeta": {
+    "consistent-ids": {
+      "optional": false
+    }
+  }
+}
diff --git a/src/fixtures/node-module-peer-optional-none/function.js b/src/fixtures/node-module-peer-optional-none/function.js
new file mode 100644
index 000000000..4295c0e6e
--- /dev/null
+++ b/src/fixtures/node-module-peer-optional-none/function.js
@@ -0,0 +1,7 @@
+try {
+  // eslint-disable-next-line node/no-missing-require
+  require('consistent-ids')
+  // eslint-disable-next-line no-empty
+} catch (error) {}
+
+module.exports = true
diff --git a/src/fixtures/node-module-peer-optional-none/package.json b/src/fixtures/node-module-peer-optional-none/package.json
new file mode 100644
index 000000000..7eb4b0ec5
--- /dev/null
+++ b/src/fixtures/node-module-peer-optional-none/package.json
@@ -0,0 +1,7 @@
+{
+  "peerDependenciesMeta": {
+    "consistent-ids": {
+      "optional": true
+    }
+  }
+}
diff --git a/src/fixtures/node-module-peer-optional/package.json b/src/fixtures/node-module-peer-optional/package.json
index c3600c138..b2131634e 100644
--- a/src/fixtures/node-module-peer-optional/package.json
+++ b/src/fixtures/node-module-peer-optional/package.json
@@ -3,9 +3,8 @@
     "consistent-ids": "0.1.1"
   },
   "peerDependenciesMeta": {
-  	"consistent-ids": {
-  		"optional": true
-  	}
+    "consistent-ids": {
+      "optional": true
+    }
   }
 }
-
diff --git a/src/go.js b/src/go.js
new file mode 100644
index 000000000..2093e765c
--- /dev/null
+++ b/src/go.js
@@ -0,0 +1,32 @@
+const { readFile } = require('fs')
+
+const { parse: parseElf } = require('elf-tools')
+const promisify = require('util.promisify')
+
+const { startZip, addZipFile, endZip } = require('./archive')
+
+const pReadFile = promisify(readFile)
+
+// Check if a file is a Go executable
+const isGoExe = async function(path) {
+  try {
+    const buffer = await pReadFile(path)
+    const { sections } = parseElf(buffer)
+    return sections.some(isGoHeader)
+  } catch (error) {
+    return false
+  }
+}
+
+const isGoHeader = function({ header: { name } }) {
+  return name === '.note.go.buildid'
+}
+
+// Zip a Go function file
+const zipGoExe = async function(srcPath, destPath, filename, stat) {
+  const { archive, output } = startZip(destPath)
+  addZipFile(archive, srcPath, filename, stat)
+  await endZip(archive, output)
+}
+
+module.exports = { isGoExe, zipGoExe }
diff --git a/src/main.js b/src/main.js
new file mode 100644
index 000000000..45392a22d
--- /dev/null
+++ b/src/main.js
@@ -0,0 +1,108 @@
+const { join, resolve, dirname, basename, extname } = require('path')
+const { readdir, lstat } = require('fs')
+
+const pMap = require('p-map')
+const promisify = require('util.promisify')
+const pathExists = require('path-exists')
+const makeDir = require('make-dir')
+const cpFile = require('cp-file')
+
+const { zipNodeJs } = require('./node')
+const { isGoExe, zipGoExe } = require('./go')
+
+const pReaddir = promisify(readdir)
+const pLstat = promisify(lstat)
+
+// Zip `srcFolder/*` (Node.js or Go files) to `destFolder/*.zip` so it can be
+// used by AWS Lambda
+const zipFunctions = async function(srcFolder, destFolder, { parallelLimit = 5, skipGo } = {}) {
+  const filenames = await listFilenames(srcFolder)
+  const srcPaths = filenames.map(filename => resolve(srcFolder, filename))
+
+  const zipped = await pMap(srcPaths, srcPath => zipFunction(srcPath, destFolder, { skipGo }), {
+    concurrency: parallelLimit
+  })
+  return zipped.filter(Boolean)
+}
+
+const listFilenames = async function(srcFolder) {
+  try {
+    return await pReaddir(srcFolder)
+  } catch (error) {
+    throw new Error(`Functions folder does not exist: ${srcFolder}`)
+  }
+}
+
+const zipFunction = async function(srcPath, destFolder, { skipGo } = {}) {
+  const { filename, extension, srcDir, stat, handler, destPath, destCopyPath } = await statFile(srcPath, destFolder)
+
+  if (filename === 'node_modules' || (stat.isDirectory() && handler === undefined)) {
+    return
+  }
+
+  if (extension === '.zip') {
+    await cpFile(srcPath, destCopyPath)
+    return { path: destCopyPath, runtime: 'js' }
+  }
+
+  if (extension === '.js' || stat.isDirectory()) {
+    await zipNodeJs(srcPath, srcDir, destPath, filename, handler, stat)
+    return { path: destPath, runtime: 'js' }
+  }
+
+  const isGoExecutable = await isGoExe(srcPath)
+
+  if (isGoExecutable && skipGo) {
+    await cpFile(srcPath, destCopyPath)
+    return { path: destCopyPath, runtime: 'go' }
+  }
+
+  if (isGoExecutable) {
+    await zipGoExe(srcPath, destPath, filename, stat)
+    return { path: destPath, runtime: 'go' }
+  }
+}
+
+const statFile = async function(srcPath, destFolder) {
+  const filename = basename(srcPath)
+  const extension = extname(srcPath)
+  const stat = await pLstat(srcPath)
+  const handler = await getHandler(srcPath, filename, stat)
+  const srcDir = stat.isDirectory() ? srcPath : dirname(srcPath)
+
+  await makeDir(destFolder)
+  const destCopyPath = join(destFolder, filename)
+  const destPath = join(destFolder, `${filename.replace(FUNCTION_EXTENSIONS, '')}.zip`)
+
+  return {
+    filename,
+    extension,
+    srcDir,
+    stat,
+    handler,
+    destCopyPath,
+    destPath
+  }
+}
+
+// Each `srcPath` can also be a directory with an `index.js` file or a file
+// using the same filename as its directory
+const getHandler = async function(srcPath, filename, stat) {
+  if (!stat.isDirectory()) {
+    return srcPath
+  }
+
+  const namedHandler = join(srcPath, `${filename}.js`)
+  if (await pathExists(namedHandler)) {
+    return namedHandler
+  }
+
+  const indexHandler = join(srcPath, 'index.js')
+  if (await pathExists(indexHandler)) {
+    return indexHandler
+  }
+}
+
+const FUNCTION_EXTENSIONS = /\.js$/
+
+module.exports = { zipFunctions, zipFunction }
diff --git a/src/main.test.js b/src/main.test.js
index 7e3f6dfab..8892c24ae 100644
--- a/src/main.test.js
+++ b/src/main.test.js
@@ -48,6 +48,16 @@ test('Ignore some excluded node modules', async t => {
   t.false(await pathExists(`${tmpDir}/node_modules/aws-sdk`))
 })
 
+test('Include most files from node modules', async t => {
+  const { tmpDir } = await zipNode(t, 'node-module-included')
+  const [mapExists, htmlExists] = await Promise.all([
+    pathExists(`${tmpDir}/src/node_modules/test/test.map`),
+    pathExists(`${tmpDir}/src/node_modules/test/test.html`)
+  ])
+  t.false(mapExists)
+  t.true(htmlExists)
+})
+
 test('Throws on runtime errors', async t => {
   await t.throwsAsync(zipNode(t, 'node-module-error'))
 })
@@ -60,18 +70,34 @@ test('Throws on missing dependencies with no optionalDependencies', async t => {
   await t.throwsAsync(zipNode(t, 'node-module-missing-package'))
 })
 
-test.skip('Ignore missing optional dependencies', async t => {
-  await zipNode(t, 'node-module-optional')
+test('Throws on missing conditional dependencies', async t => {
+  await t.throwsAsync(zipNode(t, 'node-module-missing-conditional'))
+})
+
+test("Throws on missing dependencies' dependencies", async t => {
+  await t.throwsAsync(zipNode(t, 'node-module-missing-deep'))
+})
+
+test('Ignore missing optional dependencies', async t => {
+  await zipNode(t, 'node-module-missing-optional')
 })
 
-test.skip('Ignore missing whitelisted optional dependencies', async t => {
-  await zipNode(t, 'node-module-optional-whitelist')
+test('Ignore modules conditional dependencies', async t => {
+  await zipNode(t, 'node-module-deep-conditional')
 })
 
-test.skip('Ignore missing optional peer dependencies', async t => {
+test('Ignore missing optional peer dependencies', async t => {
   await zipNode(t, 'node-module-peer-optional')
 })
 
+test('Throws on missing optional peer dependencies with no peer dependencies', async t => {
+  await t.throwsAsync(zipNode(t, 'node-module-peer-optional-none'))
+})
+
+test('Throws on missing non-optional peer dependencies', async t => {
+  await t.throwsAsync(zipNode(t, 'node-module-peer-not-optional'))
+})
+
 test('Can require local files', async t => {
   await zipNode(t, 'local-require')
 })
@@ -80,7 +106,7 @@ test('Can require local files deeply', async t => {
   await zipNode(t, 'local-deep-require')
 })
 
-test.skip('Can require local files in the parent directories', async t => {
+test('Can require local files in the parent directories', async t => {
   await zipNode(t, 'local-parent-require')
 })
 
@@ -88,23 +114,23 @@ test('Can target a directory with a handler with the same name', async t => {
   await zipNode(t, 'directory-handler')
 })
 
-test.skip('Can target a directory with an index.js file', async t => {
+test('Can target a directory with an index.js file', async t => {
   const { files, tmpDir } = await zipFixture(t, 'index-handler')
   await unzipFiles(files)
-  t.true(require(`${tmpDir}/index.js`))
+  t.true(require(`${tmpDir}/function.js`))
 })
 
-test.skip('Keeps non-required files inside the target directory', async t => {
+test('Keeps non-required files inside the target directory', async t => {
   const { tmpDir } = await zipNode(t, 'keep-dir-files')
-  t.true(await pathExists(`${tmpDir}/file.js`))
+  t.true(await pathExists(`${tmpDir}/function.js`))
 })
 
-test.skip('Ignores non-required node_modules inside the target directory', async t => {
+test('Ignores non-required node_modules inside the target directory', async t => {
   const { tmpDir } = await zipNode(t, 'ignore-dir-node-modules')
   t.false(await pathExists(`${tmpDir}/node_modules`))
 })
 
-test.skip('Ignores deep non-required node_modules inside the target directory', async t => {
+test('Ignores deep non-required node_modules inside the target directory', async t => {
   const { tmpDir } = await zipNode(t, 'ignore-deep-dir-node-modules')
   t.false(await pathExists(`${tmpDir}/deep/node_modules`))
 })
@@ -117,7 +143,7 @@ test('Works with many function files', async t => {
   await zipNode(t, 'many-functions', 6)
 })
 
-test.skip('Throws when the source folder does not exist', async t => {
+test('Throws when the source folder does not exist', async t => {
   await t.throwsAsync(zipNode(t, 'does-not-exist'), /Functions folder does not exist/)
 })
 
@@ -137,14 +163,14 @@ test('Works on empty directories', async t => {
   await zipNode(t, 'empty', 0)
 })
 
-test.skip('Works when no package.json is present', async t => {
+test('Works when no package.json is present', async t => {
   const tmpDir = await tmpName({ prefix: 'zip-it-test' })
   const files = await cpy(`${FIXTURES_DIR}/no-package-json`, `${tmpDir}/no-package-json`, { parents: true })
   const commonDir = commonPathPrefix(files)
   await zipNode(t, 'no-package-json', 1, {}, `${commonDir}/..`)
 })
 
-test.skip('Copies already zipped files', async t => {
+test('Copies already zipped files', async t => {
   const tmpDir = await tmpName({ prefix: 'zip-it-test' })
   const { files } = await zipCheckFunctions(t, 'keep-zip', tmpDir)
 
@@ -195,7 +221,7 @@ test('Can reduce parallelism', async t => {
   await zipNode(t, 'simple', 1, { parallelLimit: 1 })
 })
 
-test.skip('Can use zipFunction()', async t => {
+test('Can use zipFunction()', async t => {
   const { path: tmpDir } = await getTmpDir({ prefix: 'zip-it-test' })
   const { runtime } = await zipFunction(`${FIXTURES_DIR}/simple/function.js`, tmpDir)
   t.is(runtime, 'js')
diff --git a/src/node.js b/src/node.js
new file mode 100644
index 000000000..e8589c6da
--- /dev/null
+++ b/src/node.js
@@ -0,0 +1,69 @@
+const { lstat } = require('fs')
+const { dirname } = require('path')
+
+const pkgDir = require('pkg-dir')
+const glob = require('glob')
+const promisify = require('util.promisify')
+const commonPathPrefix = require('common-path-prefix')
+
+const { startZip, addZipFile, addZipContent, endZip } = require('./archive')
+const { getDependencies } = require('./dependencies')
+
+const pGlob = promisify(glob)
+const pLstat = promisify(lstat)
+
+// Zip a Node.js function file
+const zipNodeJs = async function(srcPath, srcDir, destPath, filename, handler, stat) {
+  const { archive, output } = startZip(destPath)
+
+  const packageRoot = await pkgDir(srcDir)
+
+  const files = await filesForFunctionZip(srcPath, filename, handler, packageRoot, stat)
+  const dirnames = files.map(dirname)
+  const commonPrefix = commonPathPrefix(dirnames)
+
+  addEntryFile(srcPath, commonPrefix, archive, filename, handler)
+
+  await Promise.all(files.map(file => zipJsFile(file, commonPrefix, archive)))
+
+  await endZip(archive, output)
+}
+
+// Retrieve the paths to the files to zip.
+// We only include the files actually needed by the function because AWS Lambda
+// has a size limit for the zipped file. It also makes cold starts faster.
+const filesForFunctionZip = async function(srcPath, filename, handler, packageRoot, stat) {
+  const [treeFiles, depFiles] = await Promise.all([getTreeFiles(srcPath, stat), getDependencies(handler, packageRoot)])
+  const files = [...treeFiles, ...depFiles]
+  const uniqueFiles = [...new Set(files)]
+  return uniqueFiles
+}
+
+// When using a directory, we include all its descendants except `node_modules`
+const getTreeFiles = function(srcPath, stat) {
+  if (!stat.isDirectory()) {
+    return [srcPath]
+  }
+
+  return pGlob(`${srcPath}/**`, {
+    ignore: `${srcPath}/**/node_modules/**`,
+    nodir: true,
+    absolute: true
+  })
+}
+
+const addEntryFile = function(srcPath, commonPrefix, archive, filename, handler) {
+  const mainPath = handler.replace(commonPrefix, 'src/')
+  const content = Buffer.from(`module.exports = require('./${mainPath}')`)
+  const entryFilename = filename.endsWith('.js') ? filename : `${filename}.js`
+
+  addZipContent(archive, content, entryFilename)
+}
+
+const zipJsFile = async function(file, commonPrefix, archive) {
+  const filename = file.replace(commonPrefix, 'src/')
+  const stat = await pLstat(file)
+  addZipFile(archive, file, filename, stat)
+}
+
+module.exports = { zipNodeJs }
diff --git a/src/zip.js b/src/zip.js
deleted file mode 100644
index 09c1ccd5a..000000000
--- a/src/zip.js
+++ /dev/null
@@ -1,183 +0,0 @@
-const path = require('path')
-const fs = require('fs')
-
-const glob = require('glob')
-const archiver = require('archiver')
-const elfTools = require('elf-tools')
-const pAll = require('p-all')
-
-const { getDependencies, findModuleDir, findHandler } = require('./finders')
-
-class Zip {
-  constructor(path) {
-    this.output = fs.createWriteStream(path)
-    this.archive = archiver('zip', { level: 9 })
-    this.archive.pipe(this.output)
-  }
-
-  addLocalFile(path, data) {
-    this.archive.file(path, data)
-  }
-
-  finalize() {
-    return new Promise((resolve, reject) => {
-      this.output.on('end', resolve)
-      this.output.on('close', resolve)
-      this.output.on('finish', resolve)
-      this.output.on('error', reject)
-      this.archive.finalize()
-    })
-  }
-}
-
-function filesForFunctionZip(functionPath) {
-  const filesToBundle = new Set()
-  if (fs.lstatSync(functionPath).isDirectory()) {
-    const moduledir = findModuleDir(functionPath)
-    const ignoreArgs = [moduledir, 'node_modules', '**'].filter(segment => segment != null)
-    glob
-      .sync(path.join(functionPath, '**'), {
-        nodir: true,
-        ignore: path.join(...ignoreArgs),
-        absolute: true
-      })
-      .forEach(file => filesToBundle.add(file))
-    if (moduledir) {
-      let handler = null
-      const namedHandler = path.join(functionPath, `${path.basename(functionPath)}.js`)
-      const indexHandler = path.join(functionPath, 'index.js')
-      if (fs.existsSync(namedHandler)) {
-        handler = namedHandler
-      } else if (fs.existsSync(indexHandler)) {
-        handler = indexHandler
-      } else {
-        throw ('Failed to find handler for ', functionPath)
-      }
-
-      getDependencies(handler, moduledir).forEach(file => filesToBundle.add(file))
-    }
-  } else {
-    filesToBundle.add(functionPath)
-    const moduledir = findModuleDir(path.dirname(functionPath))
-    if (moduledir) {
-      getDependencies(functionPath, moduledir).forEach(file => filesToBundle.add(file))
-    }
-  }
-  return filesToBundle
-}
-
-function isGoExe(file) {
-  try {
-    const buf = fs.readFileSync(file)
-    const elf = elfTools.parse(buf)
-    return elf.sections.find(s => s.header.name === '.note.go.buildid')
-  } catch (e) {
-    return false
-  }
-}
-
-function zipEntryPath(file, basedir, moduledir) {
-  return file
-    .replace(basedir, '')
-    .replace(moduledir, '')
-    .replace(/^\//, '')
-}
-
-function zipGoExe(file, zipPath) {
-  const zip = new Zip(zipPath)
-  const stat = fs.lstatSync(file)
-  zip.addLocalFile(file, {
-    name: path.basename(file),
-    mode: stat.mode,
-    date: new Date(0), // Ensure sha256 stability regardless of mtime
-    stats: stat
-  })
-  return zip.finalize()
-}
-
-function zipJs(functionPath, zipPath) {
-  const zip = new Zip(zipPath)
-  let basedir = functionPath
-  if (fs.lstatSync(functionPath).isFile()) {
-    basedir = path.dirname(basedir)
-  }
-  const moduledir = findModuleDir(basedir)
-
-  filesForFunctionZip(functionPath).forEach(file => {
-    const entryPath = zipEntryPath(file, basedir, moduledir)
-    const stat = fs.lstatSync(file)
-    zip.addLocalFile(file, {
-      name: entryPath,
-      mode: stat.mode,
-      date: new Date(0), // Ensure sha256 stability regardless of mtime
-      stats: stat
-    })
-  })
-  return zip.finalize()
-}
-
-function zipFunction(functionPath, destFolder, options) {
-  if (path.basename(functionPath) === 'node_modules') {
-    return Promise.resolve(null)
-  }
-  const zipPath = path.join(destFolder, path.basename(functionPath).replace(/\.(js|zip)$/, '') + '.zip')
-  if (path.extname(functionPath) === '.zip') {
-    fs.copyFileSync(functionPath, zipPath)
-    return Promise.resolve({
-      path: zipPath,
-      runtime: 'js'
-    })
-  }
-  const ds = fs.lstatSync(functionPath)
-  if (ds.isDirectory() || path.extname(functionPath) === '.js') {
-    if (!findHandler(functionPath)) {
-      return Promise.resolve(null)
-    }
-    return zipJs(functionPath, zipPath).then(() => {
-      return {
-        path: zipPath,
-        runtime: 'js'
-      }
-    })
-  }
-  if (isGoExe(functionPath)) {
-    if (options && options.skipGo) {
-      const goPath = path.join(destFolder, path.basename(functionPath))
-      fs.copyFileSync(functionPath, goPath)
-      return Promise.resolve({
-        path: goPath,
-        runtime: 'go'
-      })
-    }
-
-    return zipGoExe(functionPath, zipPath).then(() => {
-      return {
-        path: zipPath,
-        runtime: 'go'
-      }
-    })
-  }
-  return Promise.resolve(null)
-}
-
-function zipFunctions(srcFolder, destFolder, options) {
-  options = Object.assign(
-    {
-      parallelLimit: 5
-    },
-    options
-  )
-  return pAll(
-    fs
-      .readdirSync(srcFolder)
-      .map(file => () => zipFunction(path.resolve(path.join(srcFolder, file)), destFolder, options)),
-    { concurrency: options.parallelLimit }
-  ).then(zipped => zipped.filter(e => e))
-}
-
-module.exports = {
-  getDependencies,
-  filesForFunctionZip,
-  zipFunction,
-  zipFunctions
-}