diff --git a/clientv3/watch.go b/clientv3/watch.go
index d317010e2..98ec9a6af 100644
--- a/clientv3/watch.go
+++ b/clientv3/watch.go
@@ -1043,7 +1043,7 @@ func (pr *progressRequest) toPB() *pb.WatchRequest {
 
 func streamKeyFromCtx(ctx context.Context) string {
 	if md, ok := metadata.FromOutgoingContext(ctx); ok {
-		return fmt.Sprintf("%+v", md)
+		return fmt.Sprintf("%+v", map[string][]string(md))
 	}
 	return ""
 }