diff --git a/lib/repl.js b/lib/repl.js
index 420b9558f99700..19272f2229c702 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -1447,7 +1447,7 @@ REPLServer.prototype.defineCommand = function(keyword, cmd) {
   if (typeof cmd === 'function') {
     cmd = { action: cmd };
   } else if (typeof cmd.action !== 'function') {
-    throw new ERR_INVALID_ARG_TYPE('action', 'Function', cmd.action);
+    throw new ERR_INVALID_ARG_TYPE('cmd.action', 'Function', cmd.action);
   }
   this.commands[keyword] = cmd;
 };