diff --git a/graphene/validators/depth_limit_validator.py b/graphene/validators/depth_limit_validator.py
index 43615205..d2589700 100644
--- a/graphene/validators/depth_limit_validator.py
+++ b/graphene/validators/depth_limit_validator.py
@@ -28,7 +28,7 @@
 import re
 from typing import Callable, Dict, List, Optional, Union
 
-from graphql import GraphQLError, is_introspection_type
+from graphql import GraphQLError
 from graphql.language import (
     DefinitionNode,
     FieldNode,