diff --git a/luprex/cpp/drv/driver.cpp b/luprex/cpp/drv/driver.cpp
index 01e512bb..5710691c 100644
--- a/luprex/cpp/drv/driver.cpp
+++ b/luprex/cpp/drv/driver.cpp
@@ -227,11 +227,12 @@ class Driver {
         if (message == "truncated lua") {
             console_command_ = cmd;
         } else if (message == "white space") {
-            readline_device_.printline("white space.");
+            // no need to do anything.
         } else if (message == "slash command") {
             readline_device_.printline("slash command.");
         } else if (message.empty()) {
-            readline_device_.printline("valid lua");
+            engw.play_access(&engw, AccessKind::INVOKE_LUA_EXPR,
+                0, cmd.size(), cmd.c_str(), nullptr, nullptr);
         } else {
             readline_device_.printline(message);
         }