diff --git a/endpoints/appr/decorators.py b/endpoints/appr/decorators.py
index 5d6e78589..2de588055 100644
--- a/endpoints/appr/decorators.py
+++ b/endpoints/appr/decorators.py
@@ -2,10 +2,10 @@ import logging
 
 from functools import wraps
 
-from flask import abort
-
 from data import model
 
+from util.http import abort
+
 
 logger = logging.getLogger(__name__)
 
@@ -26,7 +26,7 @@ def disallow_for_image_repository(get_reponame_method=_get_reponame_kwargs):
       image_repo = model.repository.get_repository(namespace_name, repo_name, kind_filter='image')
       if image_repo is not None:
         logger.debug('Tried to invoked a CNR method on an image repository')
-        abort(501)
+        abort(405, message='Cannot push an application to an image repository with the same name')
       return func(*args, **kwargs)
     return wrapped
   return wrapper
diff --git a/endpoints/appr/test/test_appr_decorators.py b/endpoints/appr/test/test_appr_decorators.py
index fee7ea7cb..c71b3107c 100644
--- a/endpoints/appr/test/test_appr_decorators.py
+++ b/endpoints/appr/test/test_appr_decorators.py
@@ -1,6 +1,6 @@
 import pytest
 
-from werkzeug.exceptions import NotImplemented as NIE
+from werkzeug.exceptions import HTTPException
 
 from data import model
 from endpoints.appr import require_app_repo_read
@@ -14,6 +14,6 @@ def test_require_app_repo_read(app):
   def empty(**kwargs):
     called[0] = True
 
-  with pytest.raises(NIE):
+  with pytest.raises(HTTPException):
     empty(namespace='devtable', package_name='simple')
     assert not called[0]