diff --git a/package.json b/package.json
index a4f71413..ebaca181 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "netlify-lambda",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "Build and serve lambda function with webpack compilation",
   "homepage": "https://github.com/netlify/netlify-lambda#readme",
   "main": "bin/cmd.js",
diff --git a/yarn.lock b/yarn.lock
index 5113b6b4..71c41ba4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -196,6 +196,14 @@ babel-generator@^6.26.0:
     source-map "^0.5.6"
     trim-right "^1.0.1"
 
+babel-helper-builder-binary-assignment-operator-visitor@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-builder-binary-assignment-operator-visitor/-/babel-helper-builder-binary-assignment-operator-visitor-6.24.1.tgz#cce4517ada356f4220bcae8a02c2b346f9a56664"
+  dependencies:
+    babel-helper-explode-assignable-expression "^6.24.1"
+    babel-runtime "^6.22.0"
+    babel-types "^6.24.1"
+
 babel-helper-call-delegate@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-call-delegate/-/babel-helper-call-delegate-6.24.1.tgz#ece6aacddc76e41c3461f88bfc575bd0daa2df8d"
@@ -214,6 +222,14 @@ babel-helper-define-map@^6.24.1:
     babel-types "^6.26.0"
     lodash "^4.17.4"
 
+babel-helper-explode-assignable-expression@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-explode-assignable-expression/-/babel-helper-explode-assignable-expression-6.24.1.tgz#f25b82cf7dc10433c55f70592d5746400ac22caa"
+  dependencies:
+    babel-runtime "^6.22.0"
+    babel-traverse "^6.24.1"
+    babel-types "^6.24.1"
+
 babel-helper-function-name@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-function-name/-/babel-helper-function-name-6.24.1.tgz#d3475b8c03ed98242a25b48351ab18399d3580a9"
@@ -253,6 +269,16 @@ babel-helper-regex@^6.24.1:
     babel-types "^6.26.0"
     lodash "^4.17.4"
 
+babel-helper-remap-async-to-generator@^6.24.1:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-helper-remap-async-to-generator/-/babel-helper-remap-async-to-generator-6.24.1.tgz#5ec581827ad723fecdd381f1c928390676e4551b"
+  dependencies:
+    babel-helper-function-name "^6.24.1"
+    babel-runtime "^6.22.0"
+    babel-template "^6.24.1"
+    babel-traverse "^6.24.1"
+    babel-types "^6.24.1"
+
 babel-helper-replace-supers@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-helper-replace-supers/-/babel-helper-replace-supers-6.24.1.tgz#bf6dbfe43938d17369a213ca8a8bf74b6a90ab1a"
@@ -291,14 +317,34 @@ babel-plugin-check-es2015-constants@^6.22.0:
   dependencies:
     babel-runtime "^6.22.0"
 
+babel-plugin-syntax-async-functions@^6.8.0:
+  version "6.13.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-async-functions/-/babel-plugin-syntax-async-functions-6.13.0.tgz#cad9cad1191b5ad634bf30ae0872391e0647be95"
+
 babel-plugin-syntax-class-properties@^6.8.0:
   version "6.13.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-syntax-class-properties/-/babel-plugin-syntax-class-properties-6.13.0.tgz#d7eb23b79a317f8543962c505b827c7d6cac27de"
 
+babel-plugin-syntax-exponentiation-operator@^6.8.0:
+  version "6.13.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-exponentiation-operator/-/babel-plugin-syntax-exponentiation-operator-6.13.0.tgz#9ee7e8337290da95288201a6a57f4170317830de"
+
 babel-plugin-syntax-object-rest-spread@^6.8.0:
   version "6.13.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-syntax-object-rest-spread/-/babel-plugin-syntax-object-rest-spread-6.13.0.tgz#fd6536f2bce13836ffa3a5458c4903a597bb3bf5"
 
+babel-plugin-syntax-trailing-function-commas@^6.22.0:
+  version "6.22.0"
+  resolved "https://registry.yarnpkg.com/babel-plugin-syntax-trailing-function-commas/-/babel-plugin-syntax-trailing-function-commas-6.22.0.tgz#ba0360937f8d06e40180a43fe0d5616fff532cf3"
+
+babel-plugin-transform-async-to-generator@^6.22.0:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-async-to-generator/-/babel-plugin-transform-async-to-generator-6.24.1.tgz#6536e378aff6cb1d5517ac0e40eb3e9fc8d08761"
+  dependencies:
+    babel-helper-remap-async-to-generator "^6.24.1"
+    babel-plugin-syntax-async-functions "^6.8.0"
+    babel-runtime "^6.22.0"
+
 babel-plugin-transform-class-properties@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-class-properties/-/babel-plugin-transform-class-properties-6.24.1.tgz#6a79763ea61d33d36f37b611aa9def81a81b46ac"
@@ -320,7 +366,7 @@ babel-plugin-transform-es2015-block-scoped-functions@^6.22.0:
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-block-scoping@^6.24.1:
+babel-plugin-transform-es2015-block-scoping@^6.23.0:
   version "6.26.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-block-scoping/-/babel-plugin-transform-es2015-block-scoping-6.26.0.tgz#d70f5299c1308d05c12f463813b0a09e73b1895f"
   dependencies:
@@ -330,7 +376,7 @@ babel-plugin-transform-es2015-block-scoping@^6.24.1:
     babel-types "^6.26.0"
     lodash "^4.17.4"
 
-babel-plugin-transform-es2015-classes@^6.24.1:
+babel-plugin-transform-es2015-classes@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-classes/-/babel-plugin-transform-es2015-classes-6.24.1.tgz#5a4c58a50c9c9461e564b4b2a3bfabc97a2584db"
   dependencies:
@@ -344,33 +390,33 @@ babel-plugin-transform-es2015-classes@^6.24.1:
     babel-traverse "^6.24.1"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-computed-properties@^6.24.1:
+babel-plugin-transform-es2015-computed-properties@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-computed-properties/-/babel-plugin-transform-es2015-computed-properties-6.24.1.tgz#6fe2a8d16895d5634f4cd999b6d3480a308159b3"
   dependencies:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-destructuring@^6.22.0:
+babel-plugin-transform-es2015-destructuring@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-destructuring/-/babel-plugin-transform-es2015-destructuring-6.23.0.tgz#997bb1f1ab967f682d2b0876fe358d60e765c56d"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-duplicate-keys@^6.24.1:
+babel-plugin-transform-es2015-duplicate-keys@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-duplicate-keys/-/babel-plugin-transform-es2015-duplicate-keys-6.24.1.tgz#73eb3d310ca969e3ef9ec91c53741a6f1576423e"
   dependencies:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-for-of@^6.22.0:
+babel-plugin-transform-es2015-for-of@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-for-of/-/babel-plugin-transform-es2015-for-of-6.23.0.tgz#f47c95b2b613df1d3ecc2fdb7573623c75248691"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-function-name@^6.24.1:
+babel-plugin-transform-es2015-function-name@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-function-name/-/babel-plugin-transform-es2015-function-name-6.24.1.tgz#834c89853bc36b1af0f3a4c5dbaa94fd8eacaa8b"
   dependencies:
@@ -384,7 +430,7 @@ babel-plugin-transform-es2015-literals@^6.22.0:
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-modules-amd@^6.24.1:
+babel-plugin-transform-es2015-modules-amd@^6.22.0, babel-plugin-transform-es2015-modules-amd@^6.24.1:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-amd/-/babel-plugin-transform-es2015-modules-amd-6.24.1.tgz#3b3e54017239842d6d19c3011c4bd2f00a00d154"
   dependencies:
@@ -392,7 +438,7 @@ babel-plugin-transform-es2015-modules-amd@^6.24.1:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-modules-commonjs@^6.24.1:
+babel-plugin-transform-es2015-modules-commonjs@^6.23.0, babel-plugin-transform-es2015-modules-commonjs@^6.24.1:
   version "6.26.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-commonjs/-/babel-plugin-transform-es2015-modules-commonjs-6.26.0.tgz#0d8394029b7dc6abe1a97ef181e00758dd2e5d8a"
   dependencies:
@@ -401,7 +447,7 @@ babel-plugin-transform-es2015-modules-commonjs@^6.24.1:
     babel-template "^6.26.0"
     babel-types "^6.26.0"
 
-babel-plugin-transform-es2015-modules-systemjs@^6.24.1:
+babel-plugin-transform-es2015-modules-systemjs@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-systemjs/-/babel-plugin-transform-es2015-modules-systemjs-6.24.1.tgz#ff89a142b9119a906195f5f106ecf305d9407d23"
   dependencies:
@@ -409,7 +455,7 @@ babel-plugin-transform-es2015-modules-systemjs@^6.24.1:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-modules-umd@^6.24.1:
+babel-plugin-transform-es2015-modules-umd@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-modules-umd/-/babel-plugin-transform-es2015-modules-umd-6.24.1.tgz#ac997e6285cd18ed6176adb607d602344ad38468"
   dependencies:
@@ -417,14 +463,14 @@ babel-plugin-transform-es2015-modules-umd@^6.24.1:
     babel-runtime "^6.22.0"
     babel-template "^6.24.1"
 
-babel-plugin-transform-es2015-object-super@^6.24.1:
+babel-plugin-transform-es2015-object-super@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-object-super/-/babel-plugin-transform-es2015-object-super-6.24.1.tgz#24cef69ae21cb83a7f8603dad021f572eb278f8d"
   dependencies:
     babel-helper-replace-supers "^6.24.1"
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-parameters@^6.24.1:
+babel-plugin-transform-es2015-parameters@^6.23.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-parameters/-/babel-plugin-transform-es2015-parameters-6.24.1.tgz#57ac351ab49caf14a97cd13b09f66fdf0a625f2b"
   dependencies:
@@ -435,7 +481,7 @@ babel-plugin-transform-es2015-parameters@^6.24.1:
     babel-traverse "^6.24.1"
     babel-types "^6.24.1"
 
-babel-plugin-transform-es2015-shorthand-properties@^6.24.1:
+babel-plugin-transform-es2015-shorthand-properties@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-shorthand-properties/-/babel-plugin-transform-es2015-shorthand-properties-6.24.1.tgz#24f875d6721c87661bbd99a4622e51f14de38aa0"
   dependencies:
@@ -448,7 +494,7 @@ babel-plugin-transform-es2015-spread@^6.22.0:
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-sticky-regex@^6.24.1:
+babel-plugin-transform-es2015-sticky-regex@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-sticky-regex/-/babel-plugin-transform-es2015-sticky-regex-6.24.1.tgz#00c1cdb1aca71112cdf0cf6126c2ed6b457ccdbc"
   dependencies:
@@ -462,13 +508,13 @@ babel-plugin-transform-es2015-template-literals@^6.22.0:
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-typeof-symbol@^6.22.0:
+babel-plugin-transform-es2015-typeof-symbol@^6.23.0:
   version "6.23.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-typeof-symbol/-/babel-plugin-transform-es2015-typeof-symbol-6.23.0.tgz#dec09f1cddff94b52ac73d505c84df59dcceb372"
   dependencies:
     babel-runtime "^6.22.0"
 
-babel-plugin-transform-es2015-unicode-regex@^6.24.1:
+babel-plugin-transform-es2015-unicode-regex@^6.22.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-es2015-unicode-regex/-/babel-plugin-transform-es2015-unicode-regex-6.24.1.tgz#d38b12f42ea7323f729387f18a7c5ae1faeb35e9"
   dependencies:
@@ -476,6 +522,14 @@ babel-plugin-transform-es2015-unicode-regex@^6.24.1:
     babel-runtime "^6.22.0"
     regexpu-core "^2.0.0"
 
+babel-plugin-transform-exponentiation-operator@^6.22.0:
+  version "6.24.1"
+  resolved "https://registry.yarnpkg.com/babel-plugin-transform-exponentiation-operator/-/babel-plugin-transform-exponentiation-operator-6.24.1.tgz#2ab0c9c7f3098fa48907772bb813fe41e8de3a0e"
+  dependencies:
+    babel-helper-builder-binary-assignment-operator-visitor "^6.24.1"
+    babel-plugin-syntax-exponentiation-operator "^6.8.0"
+    babel-runtime "^6.22.0"
+
 babel-plugin-transform-object-assign@^6.22.0:
   version "6.22.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-object-assign/-/babel-plugin-transform-object-assign-6.22.0.tgz#f99d2f66f1a0b0d498e346c5359684740caa20ba"
@@ -489,7 +543,7 @@ babel-plugin-transform-object-rest-spread@^6.26.0:
     babel-plugin-syntax-object-rest-spread "^6.8.0"
     babel-runtime "^6.26.0"
 
-babel-plugin-transform-regenerator@^6.24.1:
+babel-plugin-transform-regenerator@^6.22.0:
   version "6.26.0"
   resolved "https://registry.yarnpkg.com/babel-plugin-transform-regenerator/-/babel-plugin-transform-regenerator-6.26.0.tgz#e0703696fbde27f0a3efcacf8b4dca2f7b3a8f2f"
   dependencies:
@@ -502,34 +556,40 @@ babel-plugin-transform-strict-mode@^6.24.1:
     babel-runtime "^6.22.0"
     babel-types "^6.24.1"
 
-babel-preset-es2015@^6.24.1:
-  version "6.24.1"
-  resolved "https://registry.yarnpkg.com/babel-preset-es2015/-/babel-preset-es2015-6.24.1.tgz#d44050d6bc2c9feea702aaf38d727a0210538939"
+babel-preset-env@^1.6.1:
+  version "1.6.1"
+  resolved "https://registry.yarnpkg.com/babel-preset-env/-/babel-preset-env-1.6.1.tgz#a18b564cc9b9afdf4aae57ae3c1b0d99188e6f48"
   dependencies:
     babel-plugin-check-es2015-constants "^6.22.0"
+    babel-plugin-syntax-trailing-function-commas "^6.22.0"
+    babel-plugin-transform-async-to-generator "^6.22.0"
     babel-plugin-transform-es2015-arrow-functions "^6.22.0"
     babel-plugin-transform-es2015-block-scoped-functions "^6.22.0"
-    babel-plugin-transform-es2015-block-scoping "^6.24.1"
-    babel-plugin-transform-es2015-classes "^6.24.1"
-    babel-plugin-transform-es2015-computed-properties "^6.24.1"
-    babel-plugin-transform-es2015-destructuring "^6.22.0"
-    babel-plugin-transform-es2015-duplicate-keys "^6.24.1"
-    babel-plugin-transform-es2015-for-of "^6.22.0"
-    babel-plugin-transform-es2015-function-name "^6.24.1"
+    babel-plugin-transform-es2015-block-scoping "^6.23.0"
+    babel-plugin-transform-es2015-classes "^6.23.0"
+    babel-plugin-transform-es2015-computed-properties "^6.22.0"
+    babel-plugin-transform-es2015-destructuring "^6.23.0"
+    babel-plugin-transform-es2015-duplicate-keys "^6.22.0"
+    babel-plugin-transform-es2015-for-of "^6.23.0"
+    babel-plugin-transform-es2015-function-name "^6.22.0"
     babel-plugin-transform-es2015-literals "^6.22.0"
-    babel-plugin-transform-es2015-modules-amd "^6.24.1"
-    babel-plugin-transform-es2015-modules-commonjs "^6.24.1"
-    babel-plugin-transform-es2015-modules-systemjs "^6.24.1"
-    babel-plugin-transform-es2015-modules-umd "^6.24.1"
-    babel-plugin-transform-es2015-object-super "^6.24.1"
-    babel-plugin-transform-es2015-parameters "^6.24.1"
-    babel-plugin-transform-es2015-shorthand-properties "^6.24.1"
+    babel-plugin-transform-es2015-modules-amd "^6.22.0"
+    babel-plugin-transform-es2015-modules-commonjs "^6.23.0"
+    babel-plugin-transform-es2015-modules-systemjs "^6.23.0"
+    babel-plugin-transform-es2015-modules-umd "^6.23.0"
+    babel-plugin-transform-es2015-object-super "^6.22.0"
+    babel-plugin-transform-es2015-parameters "^6.23.0"
+    babel-plugin-transform-es2015-shorthand-properties "^6.22.0"
     babel-plugin-transform-es2015-spread "^6.22.0"
-    babel-plugin-transform-es2015-sticky-regex "^6.24.1"
+    babel-plugin-transform-es2015-sticky-regex "^6.22.0"
     babel-plugin-transform-es2015-template-literals "^6.22.0"
-    babel-plugin-transform-es2015-typeof-symbol "^6.22.0"
-    babel-plugin-transform-es2015-unicode-regex "^6.24.1"
-    babel-plugin-transform-regenerator "^6.24.1"
+    babel-plugin-transform-es2015-typeof-symbol "^6.23.0"
+    babel-plugin-transform-es2015-unicode-regex "^6.22.0"
+    babel-plugin-transform-exponentiation-operator "^6.22.0"
+    babel-plugin-transform-regenerator "^6.22.0"
+    browserslist "^2.1.2"
+    invariant "^2.2.2"
+    semver "^5.3.0"
 
 babel-register@^6.26.0:
   version "6.26.0"
@@ -715,6 +775,13 @@ browserify-zlib@^0.1.4:
   dependencies:
     pako "~0.2.0"
 
+browserslist@^2.1.2:
+  version "2.11.3"
+  resolved "https://registry.yarnpkg.com/browserslist/-/browserslist-2.11.3.tgz#fe36167aed1bbcde4827ebfe71347a2cc70b99b2"
+  dependencies:
+    caniuse-lite "^1.0.30000792"
+    electron-to-chromium "^1.3.30"
+
 buffer-xor@^1.0.3:
   version "1.0.3"
   resolved "https://registry.yarnpkg.com/buffer-xor/-/buffer-xor-1.0.3.tgz#26e61ed1422fb70dd42e6e36729ed51d855fe8d9"
@@ -747,6 +814,10 @@ camelcase@^4.1.0:
   version "4.1.0"
   resolved "https://registry.yarnpkg.com/camelcase/-/camelcase-4.1.0.tgz#d545635be1e33c542649c69173e5de6acfae34dd"
 
+caniuse-lite@^1.0.30000792:
+  version "1.0.30000830"
+  resolved "https://registry.yarnpkg.com/caniuse-lite/-/caniuse-lite-1.0.30000830.tgz#cb96b8a2dd3cbfe04acea2af3c4e894249095328"
+
 caseless@~0.12.0:
   version "0.12.0"
   resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
@@ -1020,6 +1091,10 @@ ee-first@1.1.1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/ee-first/-/ee-first-1.1.1.tgz#590c61156b0ae2f4f0255732a158b266bc56b21d"
 
+electron-to-chromium@^1.3.30:
+  version "1.3.42"
+  resolved "https://registry.yarnpkg.com/electron-to-chromium/-/electron-to-chromium-1.3.42.tgz#95c33bf01d0cc405556aec899fe61fd4d76ea0f9"
+
 elliptic@^6.0.0:
   version "6.4.0"
   resolved "https://registry.yarnpkg.com/elliptic/-/elliptic-6.4.0.tgz#cac9af8762c85836187003c8dfe193e5e2eae5df"