diff --git a/components/drivers/serial/serial_v2.c b/components/drivers/serial/serial_v2.c
index 1d7a556bf2..5d6f2a8be3 100644
--- a/components/drivers/serial/serial_v2.c
+++ b/components/drivers/serial/serial_v2.c
@@ -684,6 +684,9 @@ static rt_err_t rt_serial_tx_enable(struct rt_device        *dev,
                     (sizeof(struct rt_serial_tx_fifo));
             RT_ASSERT(tx_fifo != RT_NULL);
 
+            /* Init rb.buffer_ptr to RT_NULL, in rt_serial_write() need check it
+             * otherwise buffer_ptr maybe a random value, as rt_malloc not init memory */
+            tx_fifo->rb.buffer_ptr = RT_NULL;
             serial->serial_tx = tx_fifo;
 
 #ifndef RT_USING_DEVICE_OPS
diff --git a/components/drivers/usb/usbdevice/class/cdc_vcom.c b/components/drivers/usb/usbdevice/class/cdc_vcom.c
index 0d65b0cdc5..b513394364 100644
--- a/components/drivers/usb/usbdevice/class/cdc_vcom.c
+++ b/components/drivers/usb/usbdevice/class/cdc_vcom.c
@@ -755,7 +755,11 @@ static rt_ssize_t _vcom_rb_block_put(struct vcom *data, const rt_uint8_t *buf, r
     return size;
 }
 
-static rt_ssize_t _vcom_tx(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+#ifdef RT_USING_SERIAL_V1
+static rt_size_t _vcom_tx(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, int direction)
+#else
+static rt_size_t _vcom_tx(struct rt_serial_device *serial, rt_uint8_t *buf, rt_size_t size, rt_uint32_t tx_flag)
+#endif
 {
     struct ufunction *func;
     struct vcom *data;