--- a/src/devices/wifi/mac-low.cc	Wed Aug 25 17:42:52 2010 +0200
+++ b/src/devices/wifi/mac-low.cc	Wed Aug 25 21:31:43 2010 +0200
@@ -987,7 +987,7 @@
     {
       txTime += m_phy->CalculateTxDuration (GetRtsSize (), rtsMode, WIFI_PREAMBLE_LONG);
       txTime += GetCtsDuration (hdr->GetAddr1 (), rtsMode);
-      txTime += GetSifs ().To () * 2;
+      txTime += Time (GetSifs () * 2);
     }
   uint32_t dataSize = GetSize (packet, hdr);
   txTime += m_phy->CalculateTxDuration (dataSize, dataMode, WIFI_PREAMBLE_LONG);
@@ -1047,7 +1047,7 @@
           cts.SetType (WIFI_MAC_CTL_CTS);
           Time navCounterResetCtsMissedDelay = 
             m_phy->CalculateTxDuration (cts.GetSerializedSize (), txMode, preamble) +
-            2 * GetSifs ().To () + 2 * GetSlotTime ().To ();
+            Time (2 * GetSifs ()) + Time (2 * GetSlotTime ());
           m_navCounterResetCtsMissed = Simulator::Schedule (navCounterResetCtsMissedDelay,
                                                             &MacLow::NavCounterResetCtsMissed, this,
                                                             Simulator::Now ());