--- iscsi.c.orig	2018-01-27 08:43:26.937858000 -0700
+++ iscsi.c	2018-01-27 09:15:39.631501000 -0700
@@ -1071,17 +1071,23 @@
 }
 
 
-#if __FreeBSD_version >= 1100000
+#if __FreeBSD_version >= 1200051
+static void
+isboot_free_mbufext(struct mbuf *m)
+{
+	void *p = m->m_ext.ext_arg1;
+#elif __FreeBSD_version >= 1100000
 static void
 isboot_free_mbufext(struct mbuf *m, void *p, void *optarg)
 #elif __FreeBSD_version >= 1000050 && __FreeBSD_version < 1100000
 static int
 isboot_free_mbufext(struct mbuf *m, void *p, void *optarg)
+{
 #else
 static void
 isboot_free_mbufext(void *p, void *optarg)
-#endif
 {
+#endif
 
 	ISBOOT_TRACE("isboot_free_mbufext\n");
 	if (p == NULL)