"if match(x) >= 0:" smells of regex matching; should use "if match(x):"
diff --git a/Lib/mhlib.py b/Lib/mhlib.py
index 85bf2cd..5de1538 100644
--- a/Lib/mhlib.py
+++ b/Lib/mhlib.py
@@ -284,7 +284,7 @@
         match = numericprog.match
         append = messages.append
         for name in os.listdir(self.getfullname()):
-            if match(name) >= 0:
+            if match(name):
                 append(name)
         messages = map(string.atoi, messages)
         messages.sort()