=== modified file 'pybindgen/overloading.py'
--- pybindgen/overloading.py	2014-09-14 15:39:02 +0000
+++ pybindgen/overloading.py	2015-07-01 21:17:38 +0000
@@ -274,7 +274,10 @@
                             NotSupportedError):
                         pass
             # check available docstrings for the overloads
-            docstrings_set = {wrap.docstring for wrap in self.all_wrappers if wrap.docstring is not None}
+            docstrings_set = {}
+            for wrap in self.all_wrappers:
+                if wrap.docstring is not None:
+                    docstrings_set.add (wrap.docstring)
             docstring = None
             if len(docstrings_set) is 1:
                 docstring = docstrings_set.pop()