diff --git a/SMILEBASIC/petitcomputer.d b/SMILEBASIC/petitcomputer.d
index aa7754d..49559fb 100644
--- a/SMILEBASIC/petitcomputer.d
+++ b/SMILEBASIC/petitcomputer.d
@@ -1531,7 +1531,7 @@ class PetitComputer
         {
             return "";
         }
-        auto result = keybuffer[(keybufferpos - keybufferlen)];
+        auto result = keybuffer[(keybufferpos - keybufferlen) % keybuffer.length];
         keybufferlen--;
         return result.key.to!wstring;
     }