diff --git a/mayan/apps/rest_api/classes.py b/mayan/apps/rest_api/classes.py
index d22866aed5..ffc96cba7c 100644
--- a/mayan/apps/rest_api/classes.py
+++ b/mayan/apps/rest_api/classes.py
@@ -24,7 +24,7 @@ class APIEndPoint(object):
         self.name = name
         self.endpoints = []
         try:
-            api_urls = load_backend('{}.urls.api_urls'.format(app_name or name))
+            api_urls = load_backend('{0}.urls.api_urls'.format(app_name or name))
         except Exception:
             if settings.DEBUG:
                 raise