diff --git a/package.json b/package.json
index 97ada04d18..2d8e75a249 100644
--- a/package.json
+++ b/package.json
@@ -58,10 +58,8 @@
     "rollup-plugin-babel": "^4.0.0-beta.0",
     "rollup-plugin-node-resolve": "^3.0.2",
     "rollup-stream": "^1.24.1",
-    "semver": "^5.0.0",
     "through2": "^2.0.0",
     "uglify-js": "^2.4.16",
-    "util.promisify": "^1.0.0",
     "vinyl-buffer": "^1.0.1",
     "vinyl-source-stream": "^2.0.0",
     "webpack": "^3.4.1",
diff --git a/scripts/tests/test262/run_babylon_test262_utils.js b/scripts/tests/test262/run_babylon_test262_utils.js
index 3b30125312..e34aaa82d1 100644
--- a/scripts/tests/test262/run_babylon_test262_utils.js
+++ b/scripts/tests/test262/run_babylon_test262_utils.js
@@ -2,7 +2,7 @@
 
 const fs = require("graceful-fs");
 const path = require("path");
-const promisify = require("util.promisify");
+const promisify = require("util").promisify;
 const pfs = {
   readFile: promisify(fs.readFile),
   writeFile: promisify(fs.writeFile),
diff --git a/yarn.lock b/yarn.lock
index 8e9ab0ec36..c060986b8a 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2569,7 +2569,7 @@ error-ex@^1.2.0, error-ex@^1.3.1:
   dependencies:
     is-arrayish "^0.2.1"
 
-es-abstract@^1.4.3, es-abstract@^1.5.1:
+es-abstract@^1.4.3:
   version "1.10.0"
   resolved "https://registry.yarnpkg.com/es-abstract/-/es-abstract-1.10.0.tgz#1ecb36c197842a00d8ee4c2dfd8646bb97d60864"
   dependencies:
@@ -5266,13 +5266,6 @@ object.defaults@^1.1.0:
     for-own "^1.0.0"
     isobject "^3.0.0"
 
-object.getownpropertydescriptors@^2.0.3:
-  version "2.0.3"
-  resolved "https://registry.yarnpkg.com/object.getownpropertydescriptors/-/object.getownpropertydescriptors-2.0.3.tgz#8758c846f5b407adab0f236e0986f14b051caa16"
-  dependencies:
-    define-properties "^1.1.2"
-    es-abstract "^1.5.1"
-
 object.map@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/object.map/-/object.map-1.0.1.tgz#cf83e59dc8fcc0ad5f4250e1f78b3b81bd801d37"
@@ -6118,7 +6111,7 @@ safe-buffer@^5.0.1, safe-buffer@^5.1.0, safe-buffer@^5.1.1, safe-buffer@~5.1.0,
   version "5.1.1"
   resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.1.1.tgz#893312af69b2123def71f57889001671eeb2c853"
 
-"semver@2 || 3 || 4 || 5", semver@^5.0.0, semver@^5.0.1, semver@^5.1.0, semver@^5.3.0:
+"semver@2 || 3 || 4 || 5", semver@^5.0.1, semver@^5.1.0, semver@^5.3.0:
   version "5.5.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.5.0.tgz#dc4bbc7a6ca9d916dee5d43516f0092b58f7b8ab"
 
@@ -6898,13 +6891,6 @@ util-deprecate@~1.0.1:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/util-deprecate/-/util-deprecate-1.0.2.tgz#450d4dc9fa70de732762fbd2d4a28981419a0ccf"
 
-util.promisify@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/util.promisify/-/util.promisify-1.0.0.tgz#440f7165a459c9a16dc145eb8e72f35687097030"
-  dependencies:
-    define-properties "^1.1.2"
-    object.getownpropertydescriptors "^2.0.3"
-
 util@0.10.3, util@^0.10.3, util@~0.10.1:
   version "0.10.3"
   resolved "https://registry.yarnpkg.com/util/-/util-0.10.3.tgz#7afb1afe50805246489e3db7fe0ed379336ac0f9"