diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index 345a405248..943dcc88c3 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -73,6 +73,8 @@ def __new__(cls, string, code=None):
 
     def __eq__(self, other):
         r = super().__eq__(other)
+        if r is NotImplemented:
+            return NotImplemented
         try:
             return r and self.code == other.code
         except AttributeError: