diff --git a/pkg/internal/directory/service_rpc.go b/pkg/internal/directory/service_rpc.go
index 9d140b7..f0ba2fa 100644
--- a/pkg/internal/directory/service_rpc.go
+++ b/pkg/internal/directory/service_rpc.go
@@ -66,6 +66,8 @@ func (v *ServiceRpcServer) AddService(ctx context.Context, info *proto.ServiceIn
 
 	if info.GetId() != clientId {
 		return nil, status.Errorf(codes.InvalidArgument, "client_id mismatch in metadata")
+	} else if len(clientId) == 0 {
+		return nil, status.Errorf(codes.InvalidArgument, "client_id must not be blank")
 	}
 
 	in := &ServiceInstance{
diff --git a/pkg/nex/const.go b/pkg/nex/const.go
index b493f31..37d91e2 100644
--- a/pkg/nex/const.go
+++ b/pkg/nex/const.go
@@ -1,5 +1,6 @@
 package nex
 
 const (
-	ServiceTypeAuth = "id"
+	ServiceTypeAuth   = "id"
+	ServiceTypePusher = "pusher"
 )