--- kernel/vm/vm_map.c	2018/04/24 18:26:07	1.1.1.1
+++ kernel/vm/vm_map.c	2018/04/24 18:32:42	1.1.1.2
@@ -1323,7 +1323,8 @@ kern_return_t vm_map_pageable(map, start
 		       (entry->vme_start < end)) {
 		    vm_map_clip_end(map, entry, end);
 
-		    entry->wired_count++;
+		    if (++entry->wired_count == 0)
+			panic("vm_map_pageable: wired_count");
 		    if (entry->wired_count == 1) {
 
 			/*