diff --git a/core/views/caves.py b/core/views/caves.py
index ad77d65..cc0d728 100644
--- a/core/views/caves.py
+++ b/core/views/caves.py
@@ -733,8 +733,8 @@ def edit_entrance(request, path="", caveslug=None, entslug=None):
         """
         slugname = f"{slug}{letter}"
         nents = Entrance.objects.filter(slug=slugname).count()
-        if not (c:= get_cave_from_slug(caveslug)): # walrus operator
-            return None
+        if not (c:= get_cave_from_slug(slug)): # walrus operator
+            return False
         print(f"check_new_slugname_ok() {slugname=} {letter=} => {nents}=(number of entrances) ")
         if nents ==  0:
             # looks good, but we need to check the CaveaAndEntrance object too