diff --git a/lib/usb_cdcacm.c b/lib/usb_cdcacm.c
index d22e2ff..dc85797 100644
--- a/lib/usb_cdcacm.c
+++ b/lib/usb_cdcacm.c
@@ -358,13 +358,12 @@ static void usb_cdcacm_data_tx_cb(usbd_device *usbd_dev, uint8_t ep)
 		uint16_t usb_length = (tx_used > USB_DATA_TRANSFER_SIZE ? USB_DATA_TRANSFER_SIZE : tx_used); // length of data to be transmitted (respect max packet size)
 		usb_length = (usb_length > (LENGTH(tx_buffer) - tx_i) ? LENGTH(tx_buffer) - tx_i : usb_length); // since here we use the source array not as ring buffer, only go up to the end
 		usb_length = usbd_ep_write_packet(usb_device, 0x82, (void*)(&tx_buffer[tx_i]), usb_length); // transmit data (put into USB FIFO)
-		tx_i = (tx_i + usb_length)%LENGTH(tx_buffer); // update location on buffer
+		tx_i = (tx_i + usb_length) % LENGTH(tx_buffer); // update location on buffer
 		tx_used -= usb_length; // update used size
 		tx_lock = false; // release lock
 	} else {
 		usbd_ep_write_packet(usb_device, usb_cdcacm_data_endpoints[1].bEndpointAddress, NULL, 0); // trigger empty tx for a later callback
 	}
-	usbd_poll(usb_device); // ensure the data gets sent
 }
 
 /** USB CDC ACM communication callback
@@ -427,12 +426,12 @@ void usb_cdcacm_putchar(char c)
 	}
 	while (tx_lock); // wait for lock to be released
 	tx_lock = true; // put lock on transmit buffer
-	if (tx_used<LENGTH(tx_buffer)) { // buffer not full
-		tx_buffer[(tx_i+tx_used)%LENGTH(tx_buffer)] = c; // put character in buffer
+	if (tx_used < LENGTH(tx_buffer)) { // buffer not full
+		tx_buffer[(tx_i + tx_used) % LENGTH(tx_buffer)] = c; // put character in buffer
 		tx_used++; // update used buffer
 	} else { // buffer full (might be that no terminal is connected to this serial)
-		tx_i = (tx_i+1)%LENGTH(tx_buffer); // shift start
-		tx_buffer[(tx_i+tx_used)%LENGTH(tx_buffer)] = c; // overwrite old data
+		tx_i = (tx_i + 1) % LENGTH(tx_buffer); // shift start
+		tx_buffer[(tx_i + tx_used) % LENGTH(tx_buffer)] = c; // overwrite old data
 	}
 	tx_lock = false; // release lock on transmit buffer
 	usb_cdcacm_data_tx_cb(NULL, 0); // send data over USB when possible