diff --git a/apps/plugins/lua/rocklib.c b/apps/plugins/lua/rocklib.c
index 4d7c5e8f04..4404598ad3 100644
--- a/apps/plugins/lua/rocklib.c
+++ b/apps/plugins/lua/rocklib.c
@@ -1052,6 +1052,11 @@ LUALIB_API int luaopen_rock(lua_State *L)
 {
     luaL_register(L, LUA_ROCKLIBNAME, rocklib);
     luaL_register(L, LUA_ROCKLIBNAME, rocklib_aux);
+#ifdef SIMULATOR /* rb.SIMULATOR = true allows checking for the SIM in lua */
+        lua_pushboolean(L, 1);
+        luaS_newlloc(L, "SIMULATOR", TSTR_INBIN);
+        lua_setfield(L, -2, "SIMULATOR");
+#endif
     lua_getglobal(L, "require");
     lua_pushstring(L, "rb_defines");
     if (lua_pcall (L, 1, 0, 0))
diff --git a/apps/plugins/lua_scripts/stars.lua b/apps/plugins/lua_scripts/stars.lua
index e05007afb6..2a46b00707 100644
--- a/apps/plugins/lua_scripts/stars.lua
+++ b/apps/plugins/lua_scripts/stars.lua
@@ -414,7 +414,11 @@ action_event(rb.actions.ACTION_NONE) -- we can call this now but not after regis
 local eva = rockev.register("action", action_event)
 local evc = rockev.register("timer", action_drift, rb.HZ/7)
 
+if not rb.SIMULATOR then
 while not action_quit() do rb.sleep(rb.HZ) end
+else -- the SIM requires lcd_update to be called from the main thread
+while not action_quit() do _lcd:update(); rb.sleep(10) end
+end
 
 if start_x and start_y then
     file = io.open(fname, "w")