diff --git a/examples/example.js b/examples/example.js
index 7fad25b..be25fca 100644
--- a/examples/example.js
+++ b/examples/example.js
@@ -58,7 +58,7 @@
 
   return this.require;
 }).call(this);
-this.require.define({"modules/program":function(exports, require, module){module.exports = function(){
+this.require.define({"modules/program.cjs":function(exports, require, module){module.exports = function(){
   alert('Long live the Programs!');
 };
 ;}});
diff --git a/examples/modules/program.module.js b/examples/modules/program.cjs.js
similarity index 100%
rename from examples/modules/program.module.js
rename to examples/modules/program.cjs.js
diff --git a/lib/sprockets/commonjs.rb b/lib/sprockets/commonjs.rb
index 09e3509..ed73299 100644
--- a/lib/sprockets/commonjs.rb
+++ b/lib/sprockets/commonjs.rb
@@ -4,11 +4,13 @@
 module Sprockets
   class CommonJS < Tilt::Template
 
-    DEFINE_WRAPPER = '%s.define({%s:' +
+    WRAPPER = '%s.define({%s:' +
                      'function(exports, require, module){' +
                      '%s' +
                      ";}});\n"
 
+    EXTENSIONS = %w{.module .cjs}
+
     class << self
       attr_accessor :default_namespace
     end
@@ -36,7 +38,7 @@ def evaluate(scope, locals, &block)
     attr_reader :namespace
 
     def commonjs_module?(scope)
-      File.extname(scope.logical_path) == '.module'
+      EXTENSIONS.include?(File.extname(scope.logical_path))
     end
 
     def module_name(scope)