diff --git a/Lib/mimify.py b/Lib/mimify.py
index c856910..3f0eeb9 100755
--- a/Lib/mimify.py
+++ b/Lib/mimify.py
@@ -448,7 +448,7 @@
         elif o == '-l':
             try:
                 MAXLEN = int(a)
-            except:
+            except (ValueError, OverflowError):
                 print usage
                 sys.exit(1)
         elif o == '-b':