diff --git a/babel-transpiler.gemspec b/babel-transpiler.gemspec
index 0ae083d..1e740fa 100644
--- a/babel-transpiler.gemspec
+++ b/babel-transpiler.gemspec
@@ -18,7 +18,7 @@ Gem::Specification.new do |s|
     'LICENSE'
   ]
 
-  s.add_dependency 'babel-source', '>= 4.0', '< 6'
+  s.add_dependency 'babel-source', '>= 4.0', '< 7'
   s.add_dependency 'execjs', '~> 2.0'
   s.add_development_dependency 'minitest', '~> 5.5'
 
diff --git a/script/build-gem b/script/build-gem
index 5dfde3c..75eb64c 100755
--- a/script/build-gem
+++ b/script/build-gem
@@ -18,17 +18,35 @@ git fetch origin
 
 git checkout --quiet "v$VERSION"
 make bootstrap build-dist
+popd
 
-DATE=$(git show --format=%at | head -n1)
+BROWSERIFY_CMD="../babel/node_modules/browserify/bin/cmd.js"
 
+mkdir -p babel-core/{node_modules,dist}
+pushd babel-core
+ln -s ../../babel/packages/babel-core node_modules/babel-core
+cat <<JS | node $BROWSERIFY_CMD --insert-global-vars global --outfile dist/babel-core.js -
+global.babel = require('babel-core');
+JS
 popd
+
+mkdir -p babel-cli/{node_modules,dist}
+pushd babel-cli
+ln -s ../../babel/packages/babel-cli node_modules/babel-cli
+cat <<JS | node $BROWSERIFY_CMD --insert-global-vars global --outfile dist/external-helpers.js -
+global.babelHelpers = require('babel-cli/lib/babel-external-helpers');
+JS
 popd
 
+popd
+
+DATE=$(git show --format=%at | head -n1)
+
 dir="tmp/babel-source-$VERSION"
 mkdir -p "$dir/lib/babel"
-cp "tmp/babel/packages/babel/dist/browser.js" "$dir/lib/babel.js"
-cp "tmp/babel/packages/babel/dist/external-helpers.js" "$dir/lib/babel/external-helpers.js"
-cp "tmp/babel/packages/babel/dist/polyfill.js" "$dir/lib/babel/polyfill.js"
+cp "tmp/babel-core/dist/babel-core.js" "$dir/lib/babel.js"
+cp "tmp/babel-cli/dist/external-helpers.js" "$dir/lib/babel/external-helpers.js" # 
+cp "tmp/babel/packages/babel-polyfill/dist/polyfill.js" "$dir/lib/babel/polyfill.js"
 
 cp "tmp/babel/LICENSE" "$dir/LICENSE"
 ./script/eval-erb-template "babel-source.gemspec.erb" "$GEM_VERSION" "$DATE" > "$dir/babel-source.gemspec"