--- C:/Python26/Lib/csv.py	Mon Sep 08 11:58:32 2008
+++ C:/Python26/Lib/csv-fixed.py	Wed Oct 30 11:41:22 2013
@@ -137,7 +137,8 @@
             wrong_fields = [k for k in rowdict if k not in self.fieldnames]
             if wrong_fields:
                 raise ValueError("dict contains fields not in fieldnames: " +
-                                 ", ".join(wrong_fields))
+                                 ", ".join(repr(wrong_field) for wrong_field
+                                           in wrong_fields))
         return [rowdict.get(key, self.restval) for key in self.fieldnames]
 
     def writerow(self, rowdict):