diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 2bb8c91..6f91a8a 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1644,6 +1644,14 @@
 	}
 
 	bf->bf_buf_addr = bf->bf_dmacontext;
+
+	/* tag if this is a nullfunc frame to enable PS when AP acks it */
+	if (ieee80211_is_nullfunc(fc) && ieee80211_has_pm(fc)) {
+		bf->bf_isnullfunc = true;
+		sc->sc_flags &= ~SC_OP_NULLFUNC_COMPLETED;
+	} else
+		bf->bf_isnullfunc = false;
+
 	return 0;
 }
 
@@ -2039,6 +2047,19 @@
 		}
 
 		/*
+		 * We now know the nullfunc frame has been ACKed so we
+		 * can disable RX.
+		 */
+		if (bf->bf_isnullfunc &&
+		    (ds->ds_txstat.ts_status & ATH9K_TX_ACKED)) {
+			if ((sc->sc_flags & SC_OP_PS_ENABLED)) {
+				sc->ps_enabled = true;
+				ath9k_hw_setrxabort(sc->sc_ah, 1);
+			} else
+				sc->sc_flags |= SC_OP_NULLFUNC_COMPLETED;
+		}
+
+		/*
 		 * Remove ath_buf's of the same transmit unit from txq,
 		 * however leave the last descriptor back as the holding
 		 * descriptor for hw.