Index: tracspamfilter/model.py
===================================================================
--- tracspamfilter/model.py	(Revision 5515)
+++ tracspamfilter/model.py	(Arbeitskopie)
@@ -79,7 +79,7 @@
         """Revert the encoding done by `_encode_content` and return an unicode
         string"""
         try:
-            return to_unicode(content.decode('base64'))
+            return to_unicode(str(content).decode('base64'))
         except (UnicodeEncodeError, binascii.Error):
             # cope with legacy content (stored before base64 encoding)
             return to_unicode(content)