Index: /branches/boinc_core_release_6_12/client/cs_cmdline.cpp
===================================================================
--- /branches/boinc_core_release_6_12/client/cs_cmdline.cpp	(revision 22643)
+++ /branches/boinc_core_release_6_12/client/cs_cmdline.cpp	(revision 23003)
@@ -169,5 +169,6 @@
             else file_xfer_giveup_period = atoi(argv[++i]);
         } else if (ARG(gui_rpc_port)) {
-            cmdline_gui_rpc_port = atoi(argv[++i]);
+            if (i == argc-1) show_options = true;
+            else cmdline_gui_rpc_port = atoi(argv[++i]);
         } else if (ARG(help)) {
             print_options(argv[0]);