--- extension.py.orig	2012-06-01 11:44:36.693833852 +0200
+++ extension.py	2012-06-01 11:44:44.473975195 +0200
@@ -103,9 +103,9 @@
                   language=None,
                   **kw                      # To catch unknown keywords
                  ):
-        assert type(name) is StringType, "'name' must be a string"
+        assert type(name) in StringTypes, "'name' must be a string"
         assert (type(sources) is ListType and
-                map(type, sources) == [StringType]*len(sources)), \
+                all(isinstance(s,StringTypes) for s in sources)), \
                 "'sources' must be a list of strings"
 
         self.name = name