diff --git a/src/wifi/model/interference-helper.cc b/src/wifi/model/interference-helper.cc
index f6a258317..373574d48 100644
--- a/src/wifi/model/interference-helper.cc
+++ b/src/wifi/model/interference-helper.cc
@@ -283,7 +283,7 @@ InterferenceHelper::CalculatePer (Ptr<const InterferenceHelper::Event> event, Ni
   WifiMode headerMode = WifiPhy::GetPlcpHeaderMode (payloadMode, preamble);
   Time plcpHeaderStart = (*j).GetTime () + WifiPhy::GetPlcpPreambleDuration (payloadMode, preamble); //packet start time+ preamble
   Time plcpHsigHeaderStart = plcpHeaderStart + WifiPhy::GetPlcpHeaderDuration (payloadMode, preamble);//packet start time+ preamble+L SIG
-  Time plcpHtTrainingSymbolsStart = plcpHsigHeaderStart + WifiPhy::GetPlcpHtSigHeaderDuration (payloadMode, preamble);//packet start time+ preamble+L SIG+HT SIG
+  Time plcpHtTrainingSymbolsStart = plcpHsigHeaderStart + WifiPhy::GetPlcpHtSigHeaderDuration (preamble);//packet start time+ preamble+L SIG+HT SIG
   Time plcpPayloadStart =plcpHtTrainingSymbolsStart + WifiPhy::GetPlcpHtTrainingSymbolDuration (preamble,event->GetTxVector()); //packet start time+ preamble+L SIG+HT SIG+Training
   double noiseInterferenceW = (*j).GetDelta ();
   double powerW = event->GetRxPowerW ();
diff --git a/src/wifi/model/wifi-phy.cc b/src/wifi/model/wifi-phy.cc
index a815ea191..53c4967c9 100644
--- a/src/wifi/model/wifi-phy.cc
+++ b/src/wifi/model/wifi-phy.cc
@@ -170,7 +170,7 @@ WifiPhy::GetPlcpHtTrainingSymbolDuration (WifiPreamble preamble, WifiTxVector tx
 
 //return L-SIG
 Time
-WifiPhy::GetPlcpHtSigHeaderDuration (WifiMode payloadMode, WifiPreamble preamble)
+WifiPhy::GetPlcpHtSigHeaderDuration (WifiPreamble preamble)
 {
          switch (preamble)
             {
@@ -579,7 +579,7 @@ WifiPhy::CalculateTxDuration (uint32_t size, WifiTxVector txvector, WifiPreamble
   WifiMode payloadMode=txvector.GetMode();
   Time duration = GetPlcpPreambleDuration (payloadMode, preamble)
     + GetPlcpHeaderDuration (payloadMode, preamble)
-    + GetPlcpHtSigHeaderDuration (payloadMode, preamble)
+    + GetPlcpHtSigHeaderDuration (preamble)
     + GetPlcpHtTrainingSymbolDuration (preamble, txvector)
     + GetPayloadDuration (size, txvector, preamble, frequency, packetType, incFlag);
   return duration;
diff --git a/src/wifi/model/wifi-phy.h b/src/wifi/model/wifi-phy.h
index 2599d43ee..bff8b5f83 100644
--- a/src/wifi/model/wifi-phy.h
+++ b/src/wifi/model/wifi-phy.h
@@ -311,12 +311,11 @@ public:
    */
   static WifiMode GetMFPlcpHeaderMode (WifiMode payloadMode, WifiPreamble preamble);
   /** 
-   * \param payloadMode the WifiMode use for the transmission of the payload
    * \param preamble the type of preamble
    * 
    * \return the duration of the HT-SIG in Mixed Format and greenfield format PLCP header 
    */
-  static Time GetPlcpHtSigHeaderDuration (WifiMode payloadMode, WifiPreamble preamble);
+  static Time GetPlcpHtSigHeaderDuration (WifiPreamble preamble);
 
 
   /**