diff --git a/Lib/idlelib/CallTips.py b/Lib/idlelib/CallTips.py
index 606ab8e..f166867 100644
--- a/Lib/idlelib/CallTips.py
+++ b/Lib/idlelib/CallTips.py
@@ -152,7 +152,7 @@
             defaults = fob.__defaults__ or []
             defaults = list(map(lambda name: "=%s" % repr(name), defaults))
             defaults = [""] * (len(real_args) - len(defaults)) + defaults
-            items = map(lambda arg, dflt: arg + dflt, real_args, defaults)
+            items = list(map(lambda arg, dflt: arg + dflt, real_args, defaults))
             if fob.__code__.co_flags & 0x4:
                 items.append("...")
             if fob.__code__.co_flags & 0x8: