diff --git a/xos/core/models/core.xproto b/xos/core/models/core.xproto
index 19983db..2c3fbf1 100644
--- a/xos/core/models/core.xproto
+++ b/xos/core/models/core.xproto
@@ -421,7 +421,7 @@
 
 message ServiceDependency (XOSBase) {
      required manytoone provider_service->Service:provided_dependencies = 1 [help_text = "The service that provides this dependency", null=False, db_index = True, blank=False, tosca_key=True];
-     required manytoone subscriber_service->Service:subscribed_dependencies = 2 [help_text = "The services that subscribes to this dependency", null=False, db_index=True, blank=False];
+     required manytoone subscriber_service->Service:subscribed_dependencies = 2 [help_text = "The services that subscribes to this dependency", null=False, db_index=True, blank=False, tosca_key=True];
      required string connect_method = 3 [max_length = 30, help_text = "method to connect the two services", null=False, blank=False, default="none", choices = "(('none', 'None'), ('private', 'Private'), ('public', 'Public'))"];
 }