diff --git a/verda/instances/_instances.py b/verda/instances/_instances.py
index 625b14f..9e93fc2 100644
--- a/verda/instances/_instances.py
+++ b/verda/instances/_instances.py
@@ -171,8 +171,8 @@ def create(
             'description': description,
             'location_code': location,
             'os_volume': os_volume,
-            'volumes': volumes,
-            'existing_volumes': existing_volumes,
+            'volumes': volumes or [],
+            'existing_volumes': existing_volumes or [],
             'is_spot': is_spot,
             'coupon': coupon,
         }