diff --git a/rpc.go b/rpc.go
index 424736e..295abf4 100644
--- a/rpc.go
+++ b/rpc.go
@@ -22,7 +22,7 @@ func newRPCServer(netCard *NetCard) *RPCServer {
 
 func (rpc *RPCServer) run() {
 
-	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", config.Network.Self.Real))
+	lis, err := net.Listen("tcp", fmt.Sprintf("%s", config.Network.Self.Real))
 	if err != nil {
 		log.Fatalf("failed to listen: %v", err)
 	}