diff --git a/rhodecode/lib/utils2.py b/rhodecode/lib/utils2.py
--- a/rhodecode/lib/utils2.py
+++ b/rhodecode/lib/utils2.py
@@ -81,7 +81,7 @@ def __get_lem(extra_mapping=None):
             return [s.lower()]
 
     for lx, t in sorted(pygments.lexers.LEXERS.items()):
-        m = map(__clean, t[-2])
+        m = list(map(__clean, t[-2]))
         if m:
             m = reduce(lambda x, y: x + y, m)
             for ext in m: