diff --git a/endpoints/tags.py b/endpoints/tags.py
index 8b29d02b9..5242662d7 100644
--- a/endpoints/tags.py
+++ b/endpoints/tags.py
@@ -27,7 +27,7 @@ def get_tags(namespace, repository):
 
   if permission.can() or model.repository_is_public(namespace, repository):
     tags = model.list_repository_tags(namespace, repository)
-    tag_map = {tag.name: tag.image.image_id for tag in tags}
+    tag_map = {tag.name: tag.image.docker_image_id for tag in tags}
     return jsonify(tag_map)
 
   abort(403)
@@ -42,7 +42,7 @@ def get_tag(namespace, repository, tag):
 
   if permission.can() or model.repository_is_public(namespace, repository):
     tag_image = model.get_tag_image(namespace, repository, tag)
-    response = make_response(tag_image.image_id, 200)
+    response = make_response(tag_image.docker_image_id, 200)
 
   abort(403)
 
@@ -55,8 +55,8 @@ def put_tag(namespace, repository, tag):
   permission = ModifyRepositoryPermission(namespace, repository)
 
   if permission.can():
-    image_id = json.loads(request.data)
-    model.create_or_update_tag(namespace, repository, tag, image_id)
+    docker_image_id = json.loads(request.data)
+    model.create_or_update_tag(namespace, repository, tag, docker_image_id)
 
     return make_response('Created', 200)