diff --git a/moto/s3/models.py b/moto/s3/models.py
index 7373dc9e3..866c5d007 100644
--- a/moto/s3/models.py
+++ b/moto/s3/models.py
@@ -1370,7 +1370,7 @@ class S3Backend(BaseBackend):
             raise MissingKey(key_name)
         self.tagger.delete_all_tags_for_resource(key.arn)
         self.tagger.tag_resource(
-            key.arn, [{"Key": key, "Value": value} for key, value in tags.items()],
+            key.arn, [{"Key": k, "Value": v} for (k, v) in tags.items()],
         )
         return key