diff --git a/tempest/api/network/base.py b/tempest/api/network/base.py
index 93335e7..77504a2 100644
--- a/tempest/api/network/base.py
+++ b/tempest/api/network/base.py
@@ -271,6 +271,7 @@
         """Wrapper utility that returns a router interface."""
         resp, interface = cls.client.add_router_interface_with_subnet_id(
             router_id, subnet_id)
+        return interface
 
     @classmethod
     def create_vpnservice(cls, subnet_id, router_id):