diff --git a/tests/openpgp/run-tests.scm b/tests/openpgp/run-tests.scm
index 76432b736..8f9435943 100644
--- a/tests/openpgp/run-tests.scm
+++ b/tests/openpgp/run-tests.scm
@@ -1,64 +1,65 @@
 ;; Test-suite runner.
 ;;
 ;; Copyright (C) 2016 g10 Code GmbH
 ;;
 ;; This file is part of GnuPG.
 ;;
 ;; GnuPG is free software; you can redistribute it and/or modify
 ;; it under the terms of the GNU General Public License as published by
 ;; the Free Software Foundation; either version 3 of the License, or
 ;; (at your option) any later version.
 ;;
 ;; GnuPG is distributed in the hope that it will be useful,
 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 ;; GNU General Public License for more details.
 ;;
 ;; You should have received a copy of the GNU General Public License
 ;; along with this program; if not, see <http://www.gnu.org/licenses/>.
 
 (if (string=? "" (getenv "abs_top_srcdir"))
     (begin
       (echo "Environment variable 'abs_top_srcdir' not set.  Please point it to"
 	    "tests/openpgp.")
       (exit 2)))
 
 ;; Set objdir so that the tests can locate built programs.
 (setenv "objdir" (getcwd) #f)
 
 (define setup
   (make-environment-cache (test::scm
 			   #f
 			   (path-join "tests" "openpgp" "setup.scm")
 			   (in-srcdir "tests" "openpgp" "setup.scm"))))
 
 (define (qualify path variant)
   (string-append "<" variant ">" path))
 
 (define (setup* variant)
   (make-environment-cache
    (test::scm
     #f
     (qualify (path-join "tests" "openpgp" "setup.scm") variant)
     (in-srcdir "tests" "openpgp" "setup.scm")
     (string-append "--" variant))))
 
 (define setup-use-keyboxd (setup* "use-keyboxd"))
-(define use-keyboxd? (or (string=? "--use-keyboxd" (car *args*))
+(define use-keyboxd? (or (and (not (null? *args*))
+                              (string=? "--use-keyboxd" (car *args*)))
                          (string=? "keyboxd" (getenv "GPGSCM_TEST_VARIANT"))))
 
 (define tests (filter (lambda (arg) (not (string-prefix? arg "--"))) *args*))
 
 (run-tests (if (null? tests)
 	       (load-tests "tests" "openpgp")
                (if use-keyboxd?
 	           (map (lambda (name)
 		          (test::scm setup-use-keyboxd
 				     (qualify (path-join "tests" "openpgp" name)
 					      "keyboxd")
 				     (in-srcdir "tests" "openpgp" name)
                                      "--use-keyboxd")) tests)
 	           (map (lambda (name)
 		          (test::scm setup
 				     (path-join "tests" "openpgp" name)
 				     (in-srcdir "tests" "openpgp" name))) tests))))