diff --git a/make.js b/make.js
index 6d08c5676..67f4a7233 100644
--- a/make.js
+++ b/make.js
@@ -504,6 +504,9 @@ target.bundle = function(args) {
     // contains a license header, so the header of bundleContent can be removed.
     bundleContent = stripCommentHeaders('\n' + bundleContent);
 
+    // Removes AMD and CommonJS branches from UMD headers.
+    bundleContent = stripUMDHeaders(bundleContent);
+
     // Append external files last since we don't want to modify them.
     bundleContent += cat(EXT_SRC_FILES);
 
@@ -614,6 +617,14 @@ function stripCommentHeaders(content, filename) {
   return content;
 }
 
+function stripUMDHeaders(content) {
+  var reg = new RegExp(
+    'if \\(typeof define === \'function\' && define.amd\\) \\{[^}]*' +
+    '\\} else if \\(typeof exports !== \'undefined\'\\) \\{[^}]*' +
+    '\\} else ', 'g');
+  return content.replace(reg, '');
+}
+
 function cleanupJSSource(file) {
   var content = cat(file);