diff --git a/rest_framework/schemas/openapi.py b/rest_framework/schemas/openapi.py
index dcf5fb5f5..8e89db3c1 100644
--- a/rest_framework/schemas/openapi.py
+++ b/rest_framework/schemas/openapi.py
@@ -501,7 +501,7 @@ class AutoSchema(ViewInspector):
             }
 
         # Also handles serializers.HStoreField,
-        if isinstance(field, DictField):
+        if isinstance(field, serializers.DictField):
             schema = {
                 "type": "object",
                 "additionalProperties": self.map_field(field.child),