diff --git a/evennia/objects/objects.py b/evennia/objects/objects.py
index 1f2bd94021..dee5d33af3 100644
--- a/evennia/objects/objects.py
+++ b/evennia/objects/objects.py
@@ -1512,9 +1512,9 @@ class DefaultObject(ObjectDB, metaclass=TypeclassBase):
             num = 1
             if self.location:
                 num = max(0, *[
-                    int(obj.key.lstrip(key) or 0)
+                    int(obj.key.lstrip(key))
                     for obj in self.location.contents
-                    if obj.key.startswith(key)
+                    if obj.key.startswith(key) and obj.key.lstrip(key).isdigit()
                 ])+1
             return "%s%03i" % (key, num)