diff --git a/magnum/api/app.py b/magnum/api/app.py
index 1d7e8e2fd2..eef543867d 100755
--- a/magnum/api/app.py
+++ b/magnum/api/app.py
@@ -45,6 +45,7 @@ def setup_app(config=None):
         app_conf.pop('root'),
         logging=getattr(config, 'logging', {}),
         wrap_app=middleware.ParsableErrorMiddleware,
+        guess_content_type_from_ext=False,
         **app_conf
     )