diff --git a/src/mudlib/zmachine/zstackmanager.py b/src/mudlib/zmachine/zstackmanager.py
index a986733..df7350f 100644
--- a/src/mudlib/zmachine/zstackmanager.py
+++ b/src/mudlib/zmachine/zstackmanager.py
@@ -96,6 +96,8 @@ class ZRoutine:
 class ZStackBottom:
     def __init__(self):
         self.program_counter = 0  # used as a cache only
+        self.stack = []
+        self.local_vars = [0 for _ in range(15)]
 
 
 class ZStackManager: