dht/dht.go | 2 ++

diff --git a/dht/dht.go b/dht/dht.go
index bf3b3f5a7c45699cacf733a85a6da6242c0af5e7..1f4980b14b31aba15ea47a6310b11838e42b6572 100644
--- a/dht/dht.go
+++ b/dht/dht.go
@@ -483,6 +483,8 @@ 	return nil
 }
 
 func (s *Server) Ping(node *net.UDPAddr) (*transaction, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 	return s.query(node, "ping", nil)
 }