diff --git a/drivers/usb/gadget/g_dnl.c b/drivers/usb/gadget/g_dnl.c
index 45a484c4b7..4ba7c1da7c 100644
--- a/drivers/usb/gadget/g_dnl.c
+++ b/drivers/usb/gadget/g_dnl.c
@@ -49,8 +49,7 @@ static const char manufacturer[] = CONFIG_G_DNL_MANUFACTURER;
 void g_dnl_set_serialnumber(char *s)
 {
 	memset(g_dnl_serial, 0, MAX_STRING_SERIAL);
-	if (strlen(s) < MAX_STRING_SERIAL)
-		strncpy(g_dnl_serial, s, strlen(s));
+	strncpy(g_dnl_serial, s, MAX_STRING_SERIAL - 1);
 }
 
 static struct usb_device_descriptor device_desc = {