diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 8f28711cfd4e05b558624427da73505b3ba12a94..306ea322c65d84983477031f97e83a248468afa1 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1040,11 +1040,11 @@ static int ath_max_framelen(int usec, int mcs, bool ht40, bool sgi)
 	int symbols, bits;
 	int bytes = 0;
 
+	usec -= L_STF + L_LTF + L_SIG + HT_SIG + HT_STF + HT_LTF(streams);
 	symbols = sgi ? TIME_SYMBOLS_HALFGI(usec) : TIME_SYMBOLS(usec);
 	bits = symbols * bits_per_symbol[mcs % 8][ht40] * streams;
 	bits -= OFDM_PLCP_BITS;
 	bytes = bits / 8;
-	bytes -= L_STF + L_LTF + L_SIG + HT_SIG + HT_STF + HT_LTF(streams);
 	if (bytes > 65532)
 		bytes = 65532;