Index: sys/netinet/tcp_lro.h
===================================================================
--- sys/netinet/tcp_lro.h
+++ sys/netinet/tcp_lro.h
@@ -79,6 +79,7 @@
 	int		lro_flushed;
 	int		lro_bad_csum;
 	int		lro_cnt;
+	int		lro_hiwat;
 
 	struct lro_head	lro_active;
 	struct lro_head	lro_free;
Index: sys/netinet/tcp_lro.c
===================================================================
--- sys/netinet/tcp_lro.c
+++ sys/netinet/tcp_lro.c
@@ -77,6 +77,7 @@
 	lc->lro_queued = 0;
 	lc->lro_flushed = 0;
 	lc->lro_cnt = 0;
+	lc->lro_hiwat = 65535;
 	SLIST_INIT(&lc->lro_free);
 	SLIST_INIT(&lc->lro_active);
 
@@ -501,7 +502,7 @@
 		}
 
 		/* Flush now if appending will result in overflow. */
-		if (le->p_len > (65535 - tcp_data_len)) {
+		if (le->p_len > (lc->lro_hiwat - tcp_data_len)) {
 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
 			tcp_lro_flush(lc, le);
 			break;
@@ -559,7 +560,7 @@
 		 * If a possible next full length packet would cause an
 		 * overflow, pro-actively flush now.
 		 */
-		if (le->p_len > (65535 - lc->ifp->if_mtu)) {
+		if (le->p_len > (lc->lro_hiwat - lc->ifp->if_mtu)) {
 			SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
 			tcp_lro_flush(lc, le);
 		} else