diff --git a/nbhttp/websocket/dialer.go b/nbhttp/websocket/dialer.go
index ef65c5cc..7dbf0860 100644
--- a/nbhttp/websocket/dialer.go
+++ b/nbhttp/websocket/dialer.go
@@ -185,8 +185,8 @@ func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader h
 
 		nbc, ok := conn.(*nbio.Conn)
 		if !ok {
-			nbhttpConn, ok := conn.(*nbhttp.Conn)
-			if !ok {
+			nbhttpConn, ok2 := conn.(*nbhttp.Conn)
+			if !ok2 {
 				err = ErrBadHandshake
 				notifyResult(err)
 				return