diff --git a/tests/test_sandbox.c b/tests/test_sandbox.c
index 40246d8..90acdc1 100644
--- a/tests/test_sandbox.c
+++ b/tests/test_sandbox.c
@@ -12,6 +12,17 @@ START_TEST(test_create) {
   ck_assert(zathura_init(zathura));
   zathura_free(zathura);
 } END_TEST
+static void
+sandbox_setup(void)
+{
+  setup();
+
+#ifdef GDK_WINDOWING_X11
+  GdkDisplay* display = gdk_display_get_default();
+
+  ck_assert_msg(!GDK_IS_X11_DISPLAY(display), "Running under X11.");
+#endif
+}
 
 static Suite* suite_sandbox(void)
 {
@@ -20,7 +31,7 @@ static Suite* suite_sandbox(void)
 
   /* basic */
   tcase = tcase_create("basic");
-  tcase_add_checked_fixture(tcase, setup, NULL);
+  tcase_add_checked_fixture(tcase, sandbox_setup, NULL);
   tcase_add_test(tcase, test_create);
   suite_add_tcase(suite, tcase);