diff --git a/mc/client/client.go b/mc/client/client.go
index a141ff1..af68166 100644
--- a/mc/client/client.go
+++ b/mc/client/client.go
@@ -2,6 +2,7 @@ package client
 
 import (
 	"context"
+	"errors"
 	"net"
 
 	"github.com/admin-else/strom/mc/data"
@@ -21,6 +22,10 @@ func Connect(ctx context.Context, addr string, version string) (ret *proto.Conn,
 		if err != nil {
 			return
 		}
+		if s.Version.Protocol == 0 {
+			err = errors.New("server didnt return protocol version")
+			return
+		}
 		protocolVersion = s.Version.Protocol
 	} else {
 		var v data.VersionInfo