diff --git a/src/aio.c b/src/aio.c
index ee450fa..d5ca9d6 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -6,9 +6,8 @@
 static const uint8_t buf_size = 32; // needs 32 bc of overflow issue on these aios?
 
 static void aio_post(libusb_device_handle *dev, uint8_t *req, const int req_len, uint8_t *resp, const int resp_len) {
-	int transferred;
-	libusb_bulk_transfer(dev, 0x01, req, req_len, &transferred, 1000);
-	libusb_bulk_transfer(dev, 0x81, resp, resp_len, &transferred, 1000);
+	libusb_bulk_transfer(dev, 0x01, req, req_len, NULL, 1000);
+	libusb_bulk_transfer(dev, 0x81, resp, resp_len, NULL, 1000);
 }
 
 static float aio_get_water_temp(libusb_device_handle* aio) {