diff --git a/drivers/net/can/usb/ucan.c b/drivers/net/can/usb/ucan.c
index 39a63b7313a4..1ccef00388ae 100644
--- a/drivers/net/can/usb/ucan.c
+++ b/drivers/net/can/usb/ucan.c
@@ -1533,7 +1533,7 @@ static int ucan_probe(struct usb_interface *intf,
 	if (ret > 0) {
 		/* copy string while ensuring zero termination */
 		strscpy(firmware_str, up->ctl_msg_buffer->raw,
-			sizeof(union ucan_ctl_payload) + 1);
+			sizeof(union ucan_ctl_payload));
 	} else {
 		strcpy(firmware_str, "unknown");
 	}