diff --git a/Lib/calendar.py b/Lib/calendar.py
index 49e8e632e42..ee16c76110f 100644
--- a/Lib/calendar.py
+++ b/Lib/calendar.py
@@ -146,7 +146,7 @@ def monthcalendar(year, month):
 	key = `year` + month_abbr[month]
 	try:
 		return mc_cache[key]
-	except RuntimeError:
+	except IOError:
 		mc_cache[key] = ret = _monthcalendar(year, month)
 		return ret