diff --git a/swh/objstorage/api/server.py b/swh/objstorage/api/server.py
--- a/swh/objstorage/api/server.py
+++ b/swh/objstorage/api/server.py
@@ -128,7 +128,7 @@
     _cfg = config['objstorage']
     app['objstorage'] = get_objstorage(_cfg['cls'], _cfg['args'])
 
-    client_max_size = config.get('client_max_size')
+    client_max_size = config.get('client_max_size', 1024 * 1024 * 1024)
     if client_max_size:
         app._client_max_size = client_max_size