diff --git a/src/aio.c b/src/aio.c
index 4edbadb..74e5c5b 100644
--- a/src/aio.c
+++ b/src/aio.c
@@ -80,7 +80,7 @@ static float aio_get_water_temp(libusb_device_handle *dev) {
 
 static uint16_t aio_get_pump_speed(libusb_device_handle *dev) {
 	POST_AND_GET_RESP(0x31, 5);
-	return (uint8_t)(resp[3] << 8 | resp[4]);
+	return (uint16_t)(resp[3] << 8 | resp[4]);
 }
 
 static enum aio_pump_mode_t aio_get_pump_mode(libusb_device_handle *dev) {