diff -r bfed06214c2a src/core/linux/SDL_dbus.c
--- a/src/core/linux/SDL_dbus.c	Tue Aug 27 11:38:43 2019 +0200
+++ b/src/core/linux/SDL_dbus.c	Sat Sep 07 15:13:08 2019 +0900
@@ -114,17 +114,20 @@
     if (!dbus.session_conn && LoadDBUSLibrary() != -1) {
         DBusError err;
         dbus.error_init(&err);
+        /* session bus is required */
         dbus.session_conn = dbus.bus_get_private(DBUS_BUS_SESSION, &err);
-        if (!dbus.error_is_set(&err)) {
-            dbus.system_conn = dbus.bus_get_private(DBUS_BUS_SYSTEM, &err);
-        }
         if (dbus.error_is_set(&err)) {
             dbus.error_free(&err);
             SDL_DBus_Quit();
             return;  /* oh well */
         }
-        dbus.connection_set_exit_on_disconnect(dbus.system_conn, 0);
         dbus.connection_set_exit_on_disconnect(dbus.session_conn, 0);
+        /* system bus is optional */
+        dbus.system_conn = dbus.bus_get_private(DBUS_BUS_SYSTEM, &err);
+        if (!dbus.error_is_set(&err)) {
+            dbus.connection_set_exit_on_disconnect(dbus.system_conn, 0);
+        }
+        dbus.error_free(&err);
     }
 }