diff --git a/sys/vm/vm_phys.c b/sys/vm/vm_phys.c
--- a/sys/vm/vm_phys.c
+++ b/sys/vm/vm_phys.c
@@ -1213,7 +1213,7 @@
 
 	rw_wlock(&vm_phys_fictitious_reg_lock);
 	seg = RB_FIND(fict_tree, &vm_phys_fictitious_tree, &tmp);
-	if (seg->start != start || seg->end != end) {
+	if (seg == NULL || seg->start != start || seg->end != end) {
 		rw_wunlock(&vm_phys_fictitious_reg_lock);
 		panic(
 		    "Unregistering not registered fictitious range [%#jx:%#jx]",