diff --git Lib/_abcoll.py Lib/_abcoll.py
index a60d91e..e9f06a5 100644
--- Lib/_abcoll.py
+++ Lib/_abcoll.py
@@ -376,8 +376,9 @@ class Mapping(Sized, Iterable, Container):
         return ValuesView(self)
 
     def __eq__(self, other):
-        return isinstance(other, Mapping) and \
-               dict(self.items()) == dict(other.items())
+        if not isinstance(other, Mapping):
+            return NotImplemented
+        return dict(self.items()) == dict(other.items())
 
     def __ne__(self, other):
         return not (self == other)