diff --git a/src/ntp_node_time.c b/src/ntp_node_time.c
index 720ae3a3..e22f30b7 100644
--- a/src/ntp_node_time.c
+++ b/src/ntp_node_time.c
@@ -148,7 +148,7 @@ static void ntp_node_recv_cb(struct ETCP_CONN* conn, struct ll_entry* entry) {
     int was_unsynced = !ntp_time_is_synced(inst);
 
     if (was_unsynced && sender_synced) {
-        inst->ntp.offset_us    = msg->t_sender_us - t4;
+        inst->ntp.offset_us    = t4 - msg->t_sender_us;
         inst->ntp.synced       = 1;
         inst->ntp.last_sync_tb = get_time_tb();