diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c
index 91b68cb884cde..22d6018ceec3c 100644
--- a/drivers/mailbox/mailbox-test.c
+++ b/drivers/mailbox/mailbox-test.c
@@ -388,7 +388,7 @@ static int mbox_test_probe(struct platform_device *pdev)
 	tdev->tx_channel = mbox_test_request_channel(pdev, "tx");
 	tdev->rx_channel = mbox_test_request_channel(pdev, "rx");
 
-	if (!tdev->tx_channel && !tdev->rx_channel)
+	if (IS_ERR_OR_NULL(tdev->tx_channel) && IS_ERR_OR_NULL(tdev->rx_channel))
 		return -EPROBE_DEFER;
 
 	/* If Rx is not specified but has Rx MMIO, then Rx = Tx */