diff --git a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
index 58a381c..a7a6def 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn-rxon.c
@@ -528,6 +528,24 @@
 	return 0;
 }
 
+void iwlagn_config_ht40(struct ieee80211_conf *conf,
+	struct iwl_rxon_context *ctx)
+{
+	if (conf_is_ht40_minus(conf)) {
+		ctx->ht.extension_chan_offset =
+			IEEE80211_HT_PARAM_CHA_SEC_BELOW;
+		ctx->ht.is_40mhz = true;
+	} else if (conf_is_ht40_plus(conf)) {
+		ctx->ht.extension_chan_offset =
+			IEEE80211_HT_PARAM_CHA_SEC_ABOVE;
+		ctx->ht.is_40mhz = true;
+	} else {
+		ctx->ht.extension_chan_offset =
+			IEEE80211_HT_PARAM_CHA_SEC_NONE;
+		ctx->ht.is_40mhz = false;
+	}
+}
+
 int iwlagn_mac_config(struct ieee80211_hw *hw, u32 changed)
 {
 	struct iwl_priv *priv = hw->priv;
@@ -586,19 +604,11 @@
 				ctx->ht.enabled = conf_is_ht(conf);
 
 			if (ctx->ht.enabled) {
-				if (conf_is_ht40_minus(conf)) {
-					ctx->ht.extension_chan_offset =
-						IEEE80211_HT_PARAM_CHA_SEC_BELOW;
-					ctx->ht.is_40mhz = true;
-				} else if (conf_is_ht40_plus(conf)) {
-					ctx->ht.extension_chan_offset =
-						IEEE80211_HT_PARAM_CHA_SEC_ABOVE;
-					ctx->ht.is_40mhz = true;
-				} else {
-					ctx->ht.extension_chan_offset =
-						IEEE80211_HT_PARAM_CHA_SEC_NONE;
-					ctx->ht.is_40mhz = false;
-				}
+				/* if HT40 is used, it should not change
+				 * after associated except channel switch */
+				if (iwl_is_associated_ctx(ctx) &&
+				     !ctx->ht.is_40mhz)
+					iwlagn_config_ht40(conf, ctx);
 			} else
 				ctx->ht.is_40mhz = false;
 
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index 6094deab..f556451 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -2610,21 +2610,9 @@
 
 	/* Configure HT40 channels */
 	ctx->ht.enabled = conf_is_ht(conf);
-	if (ctx->ht.enabled) {
-		if (conf_is_ht40_minus(conf)) {
-			ctx->ht.extension_chan_offset =
-				IEEE80211_HT_PARAM_CHA_SEC_BELOW;
-			ctx->ht.is_40mhz = true;
-		} else if (conf_is_ht40_plus(conf)) {
-			ctx->ht.extension_chan_offset =
-				IEEE80211_HT_PARAM_CHA_SEC_ABOVE;
-			ctx->ht.is_40mhz = true;
-		} else {
-			ctx->ht.extension_chan_offset =
-				IEEE80211_HT_PARAM_CHA_SEC_NONE;
-			ctx->ht.is_40mhz = false;
-		}
-	} else
+	if (ctx->ht.enabled)
+		iwlagn_config_ht40(conf, ctx);
+	else
 		ctx->ht.is_40mhz = false;
 
 	if ((le16_to_cpu(ctx->staging.channel) != ch))
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.h b/drivers/net/wireless/iwlwifi/iwl-agn.h
index 5b936ec..3856aba 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.h
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.h
@@ -86,6 +86,8 @@
 			     struct ieee80211_vif *vif,
 			     struct ieee80211_bss_conf *bss_conf,
 			     u32 changes);
+void iwlagn_config_ht40(struct ieee80211_conf *conf,
+			struct iwl_rxon_context *ctx);
 
 /* uCode */
 int iwlagn_rx_calib_result(struct iwl_priv *priv,