diff --git a/Lib/enum.py b/Lib/enum.py
index da5a31f..ebadd9f 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -628,7 +628,7 @@
 
     @classmethod
     def _missing_(cls, value):
-        raise ValueError("%r is not a valid %s" % (value, cls.__qualname__))
+        return None
 
     def __repr__(self):
         return "<%s.%s: %r>" % (