diff --git a/src/Composer/Autoload/ClassMapGenerator.php b/src/Composer/Autoload/ClassMapGenerator.php
index bebf7c7e3..26f3cf28e 100644
--- a/src/Composer/Autoload/ClassMapGenerator.php
+++ b/src/Composer/Autoload/ClassMapGenerator.php
@@ -125,8 +125,8 @@ class ClassMapGenerator
 
         preg_match_all('{
             (?:
-                 \b(?<![\$:>])(?<type>class|interface'.$traits.') \s+ (?<name>[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)
-               | \b(?<![\$:>])(?<ns>namespace) (?<nsname>\s+[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*(?:\s*\\\\\s*[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)*)? \s*[\{;]
+                 \b(?<![\$:>])(?P<type>class|interface'.$traits.') \s+ (?P<name>[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)
+               | \b(?<![\$:>])(?P<ns>namespace) (?P<nsname>\s+[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*(?:\s*\\\\\s*[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*)*)? \s*[\{;]
             )
         }ix', $contents, $matches);