diff --git a/libguile/script.c b/libguile/script.c
index 1b9de76c6..975943670 100644
--- a/libguile/script.c
+++ b/libguile/script.c
@@ -379,6 +379,7 @@ scm_shell_usage (int fatal, char *message)
            "  -e FUNCTION    after reading script, apply FUNCTION to\n"
            "                 command line arguments\n"
            "  -ds            do -s script at this point\n"
+           "  --debug        start with debugging evaluator and backtraces\n"
 	   "  -q             inhibit loading of user init file\n"
            "  --emacs        enable Emacs protocol (experimental)\n"
            "  -h, --help     display this help and exit\n"
@@ -525,6 +526,13 @@ scm_compile_shell_switches (int argc, char **argv)
 			   tail);
 	}
 
+      else if (! strcmp (argv[i], "--debug")) /* debug eval + backtraces */
+	{
+	  SCM_DEVAL_P = 1;
+	  SCM_BACKTRACE_P = 1;
+	  SCM_RESET_DEBUG_MODE;
+	}
+
       else if (! strcmp (argv[i], "--emacs")) /* use emacs protocol */ 
 	use_emacs_interface = 1;