diff --git a/tests/test-doc-portal.c b/tests/test-doc-portal.c
index 02bf5347..cb6a620e 100644
--- a/tests/test-doc-portal.c
+++ b/tests/test-doc-portal.c
@@ -201,6 +201,9 @@ main (int argc, char **argv)
   g_test_dbus_add_service_dir (dbus, TEST_SERVICES);
   g_test_dbus_up (dbus);
 
+  /* g_test_dbus_up unsets this, so re-set */
+  g_setenv ("XDG_RUNTIME_DIR", outdir, TRUE);
+
   g_spawn_command_line_sync (DOC_PORTAL " -d", NULL, NULL, &exit_status, &error);
   g_assert_cmpint (exit_status, ==, 0);
   g_assert_no_error (error);