diff --git a/src/mudlib/zmachine/zstackmanager.py b/src/mudlib/zmachine/zstackmanager.py
index 738d152..e874484 100644
--- a/src/mudlib/zmachine/zstackmanager.py
+++ b/src/mudlib/zmachine/zstackmanager.py
@@ -199,9 +199,9 @@ class ZStackManager:
             if exiting_routine.return_addr == 0:  # type: ignore[possibly-missing-attribute]
                 # Push to stack
                 self.push_stack(return_value)
-            elif 0 < exiting_routine.return_addr < 10:  # type: ignore[possibly-missing-attribute]
+            elif 0 < exiting_routine.return_addr < 0x10:  # type: ignore[possibly-missing-attribute]
                 # Store in local var
-                self.set_local_variable(exiting_routine.return_addr, return_value)  # type: ignore[possibly-missing-attribute]
+                self.set_local_variable(exiting_routine.return_addr - 1, return_value)  # type: ignore[possibly-missing-attribute]
             else:
                 # Store in global var
                 self._memory.write_global(exiting_routine.return_addr, return_value)  # type: ignore[possibly-missing-attribute]