1 files changed, 5 insertions, 1 deletions
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py
index 3de3bda..4265369 100644
--- a/Lib/_weakrefset.py
+++ b/Lib/_weakrefset.py
@@ -66,7 +66,11 @@ class WeakSet:
         return sum(x() is not None for x in self.data)
 
     def __contains__(self, item):
-        return ref(item) in self.data
+        try:
+            wr = ref(item)
+        except TypeError:
+            return False
+        return wr in self.data
 
     def __reduce__(self):
         return (self.__class__, (list(self),),