diff --git a/src/Composer/Autoload/ClassMapGenerator.php b/src/Composer/Autoload/ClassMapGenerator.php
index b7a3902df..1ecf96bfe 100644
--- a/src/Composer/Autoload/ClassMapGenerator.php
+++ b/src/Composer/Autoload/ClassMapGenerator.php
@@ -162,7 +162,7 @@ class ClassMapGenerator
         }
 
         // strip heredocs/nowdocs
-        $contents = preg_replace('{<<<[ \t]*([\'"]?)(\w+)\\1(?:\r\n|\n|\r)(?:.*?)(?:\s+)\\2(?=\s+|[;,.)])}s', 'null', $contents);
+        $contents = preg_replace('{<<<[ \t]*([\'"]?)(\w+)\\1(?:\r\n|\n|\r)(?:.*?)(?:\r\n|\n|\r)(?:\s*)\\2(?=\s+|[;,.)])}s', 'null', $contents);
         // strip strings
         $contents = preg_replace('{"[^"\\\\]*+(\\\\.[^"\\\\]*+)*+"|\'[^\'\\\\]*+(\\\\.[^\'\\\\]*+)*+\'}s', 'null', $contents);
         // strip leading non-php code if needed