diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 652ca07ce722..a298edfa06b0 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -78,6 +78,7 @@ struct sackhint {
 					 * Total sacked bytes reported by the
 					 * receiver via sack option
 					 */
+	uint32_t	_pad1[1];	/* TBD */
 	uint64_t	_pad[1];	/* TBD */
 };