diff --git a/metropolis/node/core/clusternet/wireguard.go b/metropolis/node/core/clusternet/wireguard.go
index 4c38c79..9d14b98 100644
--- a/metropolis/node/core/clusternet/wireguard.go
+++ b/metropolis/node/core/clusternet/wireguard.go
@@ -108,7 +108,7 @@
 	if err := netlink.RouteAdd(&netlink.Route{
 		Dst:       clusterNet,
 		LinkIndex: wgInterface.Index,
-		Protocol:  common.ProtocolClusternet,
+		Protocol:  netlink.RouteProtocol(common.ProtocolClusternet),
 	}); err != nil && !os.IsExist(err) {
 		return fmt.Errorf("when creating cluster route: %w", err)
 	}