diff --git a/drivers/comedi/drivers/vmk80xx.c b/drivers/comedi/drivers/vmk80xx.c
index 46023adc5395..4536ed43f65b 100644
--- a/drivers/comedi/drivers/vmk80xx.c
+++ b/drivers/comedi/drivers/vmk80xx.c
@@ -684,7 +684,7 @@ static int vmk80xx_alloc_usb_buffers(struct comedi_device *dev)
 	if (!devpriv->usb_rx_buf)
 		return -ENOMEM;
 
-	size = max(usb_endpoint_maxp(devpriv->ep_rx), MIN_BUF_SIZE);
+	size = max(usb_endpoint_maxp(devpriv->ep_tx), MIN_BUF_SIZE);
 	devpriv->usb_tx_buf = kzalloc(size, GFP_KERNEL);
 	if (!devpriv->usb_tx_buf)
 		return -ENOMEM;