diff --git a/provides.py b/provides.py
index 2d81551..450c471 100644
--- a/provides.py
+++ b/provides.py
@@ -50,4 +50,4 @@ class CinderBackendProvides(RelationBase):
         }
         conv.set_remote(backend_name=backend_name,
                         stateless=stateless,
-                        subordinate_configuration=configuration)
+                        subordinate_configuration=json.dumps(configuration))