diff --git a/tools/bundler.js b/tools/bundler.js
index 72e91650a0..9f397ae45d 100644
--- a/tools/bundler.js
+++ b/tools/bundler.js
@@ -150,10 +150,9 @@ _.extend(PackageBundlingInfo.prototype, {
   // found in this package. We'll use handlers that are defined in
   // this package and in its immediate dependencies. ('extension'
   // should be the extension of the file without a leading dot.)
-  get_source_handler: function (filepath) {
+  get_source_handler: function (extension) {
     var self = this;
     var candidates = [];
-    var extension = files.extname(filepath);
 
     if (extension in self.pkg.extensions)
       candidates.push(self.pkg.extensions[extension]);
@@ -188,9 +187,9 @@ _.extend(PackageBundlingInfo.prototype, {
       return;
     self.files[where][rel_path] = true;
 
-    var handler = self.get_source_handler(rel_path);
-
-    if (!! handler) {
+    var ext = files.findExtension(self.api.registered_extensions(), rel_path);
+    var handler = ext && self.get_source_handler(ext.substr(1));
+    if (handler) {
       handler(self.bundle.api,
               path.join(self.pkg.source_root, rel_path),
               path.join(self.pkg.serve_root, rel_path),
diff --git a/tools/files.js b/tools/files.js
index ce37e31282..ac737c9fcb 100644
--- a/tools/files.js
+++ b/tools/files.js
@@ -85,7 +85,7 @@ var files = module.exports = {
                                   extensions, func);
           });
         });
-      } else if (!! files.findExtension(extensions, filepath)) {
+      } else if (files.findExtension(extensions, filepath)) {
         func(filepath);
       }
     });
@@ -101,7 +101,7 @@ var files = module.exports = {
         ret = ret.concat(files.file_list_sync(
           path.join(filepath, fileName), extensions));
       });
-    } else if (!! files.findExtension(extensions, filepath)) {
+    } else if (files.findExtension(extensions, filepath)) {
       ret.push(filepath);
     }
 
@@ -109,25 +109,16 @@ var files = module.exports = {
   },
 
   // given a list of extensions and a path, return the file extension
-  // provided in the list. If it doesn't find it, return false.
+  // provided in the list. If it doesn't find it, return null.
   findExtension: function (extensions, filepath) {
     var len = filepath.length;
     for (var i = 0; i < extensions.length; ++i) {
-      ext = extensions[i];
+      var ext = extensions[i];
       if (filepath.indexOf(ext, len - ext.length) !== -1){
         return ext;
       }
     }
-    return false;
-  },
-
-  // given a path, return his file extension, unlike the node native
-  // `path.extname` function, this function support multiple extensions
-  // such as `.coffee.md`. false otherwise.
-  extname: function (filepath) {
-    var basename = path.basename(filepath);
-
-    return basename.substring(basename.indexOf('.') + 1);
+    return null;
   },
 
   // given a path, returns true if it is a meteor application (has a
diff --git a/tools/run.js b/tools/run.js
index 18beb467db..e9e1a14e09 100644
--- a/tools/run.js
+++ b/tools/run.js
@@ -507,7 +507,7 @@ _.extend(DependencyWatcher.prototype, {
 
     // Source files
     if (in_any_dir(self.source_dirs) &&
-        _.indexOf(self.source_extensions, path.extname(filepath)) !== -1)
+        files.findExtension(self.source_extensions, filepath))
       return true;
 
     // Other directories and files that are included