diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
index e5cceb0..bbd249d 100644
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -69,6 +69,7 @@ s16 ath9k_hw_getchan_noise(struct ath_hw *ah, struct ath9k_channel *chan)
 
 	if (chan && chan->noisefloor) {
 		s8 delta = chan->noisefloor -
+			   ATH9K_NF_CAL_NOISE_THRESH -
 			   ath9k_hw_get_default_nf(ah, chan);
 		if (delta > 0)
 			noise += delta;
diff --git a/drivers/net/wireless/ath/ath9k/calib.h b/drivers/net/wireless/ath/ath9k/calib.h
index 3b33996d..1f2e01a 100644
--- a/drivers/net/wireless/ath/ath9k/calib.h
+++ b/drivers/net/wireless/ath/ath9k/calib.h
@@ -21,6 +21,9 @@
 
 #define AR_PHY_CCA_FILTERWINDOW_LENGTH          5
 
+/* Internal noise floor can vary by about 6db depending on the frequency */
+#define ATH9K_NF_CAL_NOISE_THRESH		6
+
 #define NUM_NF_READINGS       6
 #define ATH9K_NF_CAL_HIST_MAX 5