diff --git a/.babelrc b/.babelrc
index e77bb26..a6993db 100644
--- a/.babelrc
+++ b/.babelrc
@@ -1,4 +1,7 @@
 {
+  "plugins": [
+    "transform-object-assign",
+  ],
   "env": {
     "development": {
       "presets": [
diff --git a/package.json b/package.json
index 561afba..9c8743a 100644
--- a/package.json
+++ b/package.json
@@ -32,11 +32,11 @@
   },
   "devDependencies": {
     "abigail": "^1.6.1",
-    "assert-exception": "^1.1.0",
     "ava": "^0.14.0",
     "babel-cli": "^6.6.5",
     "babel-eslint": "^6.0.2",
     "babel-plugin-espower": "^2.1.2",
+    "babel-plugin-transform-object-assign": "^6.5.0",
     "babel-preset-es2015": "^6.6.0",
     "babel-preset-es2015-rollup": "^1.1.1",
     "babel-preset-stage-1": "^6.5.0",