diff --git a/net/colo-compare.c b/net/colo-compare.c
index b966e7e514d031f67d7ddd9a482d7d1ee4cb4d1d..e845c63f2e522e4f8f4818d23155a359fa258099 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -414,8 +414,7 @@ static void colo_compare_tcp(CompareState *s, Connection *conn)
      * can ensure that the packet's payload is acknowledged by
      * primary and secondary.
     */
-    uint32_t min_ack = conn->pack - conn->sack > 0 ?
-                       conn->sack : conn->pack;
+    uint32_t min_ack = MIN(conn->pack, conn->sack);
 
 pri:
     if (g_queue_is_empty(&conn->primary_list)) {