diff --git a/src/Composer/Autoload/ClassMapGenerator.php b/src/Composer/Autoload/ClassMapGenerator.php
index 05d5d175e..e9142c15f 100644
--- a/src/Composer/Autoload/ClassMapGenerator.php
+++ b/src/Composer/Autoload/ClassMapGenerator.php
@@ -104,7 +104,7 @@ class ClassMapGenerator
         }
 
         // return early if there is no chance of matching anything in this file
-        if (!preg_match('{\b(?:class|interface'.$traits.')\b}i', $contents)) {
+        if (!preg_match('{\b(?:class|interface'.$traits.')\s}i', $contents)) {
             return array();
         }