diff --git a/mercurial/encoding.py b/mercurial/encoding.py
index 774e2dcd0a65129f23260c0eae4a855b6bb7ed12_bWVyY3VyaWFsL2VuY29kaW5nLnB5..72c6240a4b7d294f663007f6dcc5b61c7758f533_bWVyY3VyaWFsL2VuY29kaW5nLnB5 100644
--- a/mercurial/encoding.py
+++ b/mercurial/encoding.py
@@ -169,7 +169,7 @@
     "best-effort encoding-aware case-folding of local string s"
     try:
         return s.encode('ascii').lower()
-    except UnicodeDecodeError:
+    except UnicodeError:
         pass
     try:
         if isinstance(s, localstr):