diff --git a/atusb/fw/mac.c b/atusb/fw/mac.c
index 8e1d97d..38c0cf6 100644
--- a/atusb/fw/mac.c
+++ b/atusb/fw/mac.c
@@ -154,7 +154,7 @@ static void do_tx(void *user)
 		spi_send(tx_buf[i]);
 	spi_end();
 
-	reg_write(REG_TRX_STATE, TRX_CMD_TX_START);
+	slp_tr();
 
 	txing = 1;