Index: /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceToolBox.cpp
===================================================================
--- /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceToolBox.cpp	(revision 71119)
+++ /trunk/src/VBox/Additions/common/VBoxService/VBoxServiceToolBox.cpp	(revision 71120)
@@ -1596,6 +1596,15 @@
          * when the first VBoxService argument is --use-toolbox.
          */
-        if (argc < 3 || strcmp(argv[1], "--use-toolbox"))
+        if (argc < 2 || strcmp(argv[1], "--use-toolbox"))
             return false;
+
+        /* No tool specified? Show toolbox help. */
+        if (argc < 3)
+        {
+            vgsvcToolboxShowUsage();
+            *prcExit = RTEXITCODE_SYNTAX;
+            return true;
+        }
+
         argc -= 2;
         argv += 2;