diff --git a/sys/netinet/tcp_hpts.c b/sys/netinet/tcp_hpts.c
--- a/sys/netinet/tcp_hpts.c
+++ b/sys/netinet/tcp_hpts.c
@@ -759,7 +759,8 @@
 		 * "0".
 		 */
 		counter_u64_add(combined_wheel_wrap, 1);
-		*target_slot = hpts->p_nxt_slot;
+		if (target_slot)
+			*target_slot = hpts->p_nxt_slot;
 		return (0);
 	} else {
 		/*