diff --git a/src/mudlib/zmachine/zstring.py b/src/mudlib/zmachine/zstring.py
index 5291a9c..5a73905 100644
--- a/src/mudlib/zmachine/zstring.py
+++ b/src/mudlib/zmachine/zstring.py
@@ -7,6 +7,8 @@
 
 import itertools
 
+from .zlogging import log
+
 
 class ZStringEndOfString(Exception):
     """No more data left in string."""
@@ -449,6 +451,7 @@ class ZsciiTranslator:
             if index < 32:
                 return ""
             # For undefined or unmapped characters, return a placeholder
+            log(f"Warning: undefined ZSCII character code {index}, using '?'")
             return "?"
 
     def utoz(self, char):