diff --git a/browserify-es2015/index.js b/browserify-es2015/index.js
index dac6c3e..557ee6b 100644
--- a/browserify-es2015/index.js
+++ b/browserify-es2015/index.js
@@ -45,6 +45,10 @@ module.exports = function(options) {
   var b = browserify(options.src, options.browserifyOptions)
     .transform(babelify, options.babelifyOptions);
 
+  if (options.browserifyOptions.external) {
+    b.external(options.browserifyOptions.external);
+  }
+
   if (options.watch) {
     b = watchify(b, options.watchifyOptions);
     b.on('update', bundle);
diff --git a/browserify-typescript/index.js b/browserify-typescript/index.js
index c8321f6..db4930a 100644
--- a/browserify-typescript/index.js
+++ b/browserify-typescript/index.js
@@ -39,6 +39,10 @@ module.exports = function(options) {
   var b = browserify(options.src, options.browserifyOptions)
     .plugin(tsify, options.tsifyOptions);
 
+  if (options.browserifyOptions.external) {
+    b.external(options.browserifyOptions.external);
+  }
+
   if (options.watch) {
     b = watchify(b, options.watchifyOptions);
     b.on('update', bundle);