diff --git a/Lib/mailcap.py b/Lib/mailcap.py
index bc93026..4ae13d7 100644
--- a/Lib/mailcap.py
+++ b/Lib/mailcap.py
@@ -164,7 +164,7 @@
     if MIMEtype in caps:
         entries = entries + caps[MIMEtype]
     if key is not None:
-        entries = filter(lambda e, key=key: key in e, entries)
+        entries = [e for e in entries if key in e]
     return entries
 
 def subst(field, MIMEtype, filename, plist=[]):