diff --git a/src/udev-seat.c b/src/udev-seat.c
index cdeb7fd6..d1eaed8b 100644
--- a/src/udev-seat.c
+++ b/src/udev-seat.c
@@ -375,14 +375,15 @@ libinput_udev_assign_seat(struct libinput *libinput,
 
 	if (!seat_id)
 		return -1;
-	if (input->seat_id != NULL)
-		return -1;
 
 	if (libinput->interface_backend != &interface_backend) {
 		log_bug_client(libinput, "Mismatching backends.\n");
 		return -1;
 	}
 
+	if (input->seat_id != NULL)
+		return -1;
+
 	input->seat_id = strdup(seat_id);
 
 	if (udev_input_enable(&input->base) < 0)