diff --git a/src/make-exact-spec.js b/src/make-exact-spec.js
index a5d476a..4ff7ca3 100644
--- a/src/make-exact-spec.js
+++ b/src/make-exact-spec.js
@@ -4,30 +4,88 @@ var check = require('check-more-types');
 
 describe('make exact', function () {
   var makeExact = require('./make-exact');
-
   it('is a function', function () {
     la(check.fn(makeExact));
   });
-
   it('returns false if there are no dependencies', function () {
     var needSaving = makeExact({});
     la(!needSaving);
   });
 
-  it('returns false if empty dependencies', function () {
-    var needSaving = makeExact({
-      dependencies: {}
+  describe('dependencies', function () {
+    it('returns false if empty dependencies', function () {
+      var needSaving = makeExact({
+        dependencies: {}
+      });
+      la(!needSaving);
+    });
+
+    it('returns false is exact semver', function () {
+      var needSaving = makeExact({
+        dependencies: {
+          foo: '1.0.2',
+          bar: '2.0.1'
+        }
+      });
+      la(!needSaving);
+    });
+
+    it('returns true and cleans fuzzy dependencies', function () {
+      var pkg = {
+        dependencies: {
+          foo: '^1.0.2',
+          bar: '2.0.1'
+        }
+      };
+      var needSaving = makeExact(pkg);
+      la(needSaving, 'needs saving');
+      la(pkg.dependencies.foo === '1.0.2', 'removed fuzziness');
+    });
+
+    it('returns true and cleans two fuzzy dependencies', function () {
+      var pkg = {
+        dependencies: {
+          foo: '^1.0.2',
+          bar: '~2.0.1'
+        }
+      };
+      var needSaving = makeExact(pkg);
+      la(needSaving, 'needs saving');
+      la(pkg.dependencies.foo === '1.0.2', 'removed foo fuzziness');
+      la(pkg.dependencies.bar === '2.0.1', 'removed bar fuzziness');
     });
-    la(!needSaving);
   });
 
-  it('returns false is exact semver', function () {
-    var needSaving = makeExact({
-      dependencies: {
-        foo: '1.0.2',
-        bar: '2.0.1'
-      }
+  describe('dev dependencies', function () {
+    it('returns false if empty dev dependencies', function () {
+      var needSaving = makeExact({
+        dependencies: {},
+        devDependencies: {}
+      });
+      la(!needSaving);
+    });
+
+    it('returns false is exact semver', function () {
+      var needSaving = makeExact({
+        devDependencies: {
+          foo: '1.0.2',
+          bar: '2.0.1'
+        }
+      });
+      la(!needSaving);
+    });
+
+    it('returns true and cleans two fuzzy dependencies', function () {
+      var pkg = {
+        devDependencies: {
+          foo: '^1.0.2',
+          bar: '~2.0.1'
+        }
+      };
+      var needSaving = makeExact(pkg);
+      la(needSaving, 'needs saving');
+      la(pkg.devDependencies.foo === '1.0.2', 'removed foo fuzziness');
+      la(pkg.devDependencies.bar === '2.0.1', 'removed bar fuzziness');
     });
-    la(!needSaving);
   });
 });
diff --git a/src/make-exact.js b/src/make-exact.js
index 891632d..0a0db97 100644
--- a/src/make-exact.js
+++ b/src/make-exact.js
@@ -1,14 +1,14 @@
 var isStrictSemver = require('./is-strict-semver');
 var toExact = require('./to-exact');
 
-function makeExact(pkg) {
+function makeExactDependencies(dependencies) {
   var needSaving;
-  if (pkg.dependencies) {
-    Object.keys(pkg.dependencies).forEach(function (name) {
-      var version = pkg.dependencies[name];
+  if (dependencies) {
+    Object.keys(dependencies).forEach(function (name) {
+      var version = dependencies[name];
       if (!isStrictSemver(version)) {
         version = toExact(version);
-        pkg.dependencies[name] = version;
+        dependencies[name] = version;
         needSaving = true;
       }
     });
@@ -17,4 +17,12 @@ function makeExact(pkg) {
   return needSaving;
 }
 
+function makeExact(pkg) {
+  if (!pkg) {
+    throw new Error('Missing package object');
+  }
+  return makeExactDependencies(pkg.dependencies) ||
+    makeExactDependencies(pkg.devDependencies);
+}
+
 module.exports = makeExact;