diff --git a/src/dog.c b/src/dog.c
index 8b97d5b86..b1249f484 100644
--- a/src/dog.c
+++ b/src/dog.c
@@ -490,8 +490,9 @@ mon_arrive(struct monst *mtmp, int when)
         if (t) {
             xlocale = t->tx, ylocale = t->ty;
             break;
-        } else if (iflags.debug_fuzzer && (stway = stairway_find_dir(TRUE)) != 0) {
-            /* debugfuzzer returning from knox */
+        } else if (iflags.debug_fuzzer
+                   && (stway = stairway_find_dir(!builds_up(&u.uz))) != 0) {
+            /* debugfuzzer returns from or enters another branch */
             xlocale = stway->sx, ylocale = stway->sy;
         } else if (!(u.uevent.qexpelled
                      && (Is_qstart(&u.uz0) || Is_qstart(&u.uz)))) {