diff --git a/drivers/phy/st/phy-stm32-usbphyc.c b/drivers/phy/st/phy-stm32-usbphyc.c
index 27fe92f73f33..b44afbff8616 100644
--- a/drivers/phy/st/phy-stm32-usbphyc.c
+++ b/drivers/phy/st/phy-stm32-usbphyc.c
@@ -712,7 +712,7 @@ static int stm32_usbphyc_probe(struct platform_device *pdev)
 		}
 
 		ret = of_property_read_u32(child, "reg", &index);
-		if (ret || index > usbphyc->nphys) {
+		if (ret || index >= usbphyc->nphys) {
 			dev_err(&phy->dev, "invalid reg property: %d\n", ret);
 			if (!ret)
 				ret = -EINVAL;