diff --git a/src/devices/wifi/dcf-manager-test.cc b/src/devices/wifi/dcf-manager-test.cc
index 4b4286c45..c6004a488 100644
--- a/src/devices/wifi/dcf-manager-test.cc
+++ b/src/devices/wifi/dcf-manager-test.cc
@@ -38,7 +38,7 @@ public:
 
 
 private:
-  void StartTest (uint64_t slotTime, uint64_t ackTxDuration);
+  void StartTest (uint64_t slotTime, uint64_t sifs, uint64_t ackTxDuration);
   void AddDcfState (uint32_t cwMin, uint32_t cwMax, uint32_t aifsn);
   void EndTest (void);
   void ExpectAccessGranted (uint64_t time, uint32_t from);
@@ -160,12 +160,11 @@ DcfManagerTest::ExpectCollision (uint64_t time, uint32_t from)
 }
 
 void
-DcfManagerTest::StartTest (uint64_t slotTime, uint64_t ackTxDuration)
+DcfManagerTest::StartTest (uint64_t slotTime, uint64_t sifs, uint64_t ackTxDuration)
 {
   m_dcfManager = new DcfManager ();
-  m_parameters = new MacParameters ();
-  m_parameters->SetSlotTime (MicroSeconds (slotTime));
-  m_dcfManager->SetParameters (m_parameters);
+  m_dcfManager->SetSlotTime (MicroSeconds (slotTime));
+  m_dcfManager->SetSifs (MicroSeconds (sifs));
   m_dcfManager->SetAckTxDuration (MicroSeconds (ackTxDuration));
 }
 
@@ -259,7 +258,7 @@ DcfManagerTest::RunTests (void)
 {
   m_result = true;
 
-  StartTest (1 /* slot time */, 10 /* ack tx dur */);
+  StartTest (1 /* slot time */, 3 /* sifs */, 10 /* ack tx dur */);
   AddDcfState (8 /* cwmin */, 64 /* cwmax */, 1 /* aifsn */);
   AddAccessRequest (10 /* at */ , 0 /* from */);
   ExpectAccessGranted (10 /* at */, 0 /* from */);
diff --git a/src/devices/wifi/dcf-manager.cc b/src/devices/wifi/dcf-manager.cc
index 3b53c8069..74fd21605 100644
--- a/src/devices/wifi/dcf-manager.cc
+++ b/src/devices/wifi/dcf-manager.cc
@@ -103,14 +103,20 @@ DcfManager::DcfManager ()
     m_lastTxDuration (MicroSeconds (0)),
     m_lastBusyStart (MicroSeconds (0)),
     m_lastBusyDuration (MicroSeconds (0)),
-    m_rxing (false)
-
+    m_rxing (false),
+    m_slotTime (Seconds (0.0)),
+    m_sifs (Seconds (0.0))
 {}
 
 void 
-DcfManager::SetParameters (const MacParameters *parameters)
+DcfManager::SetSlotTime (Time slotTime)
 {
-  m_parameters = parameters;
+  m_slotTime = slotTime;
+}
+void 
+DcfManager::SetSifs (Time sifs)
+{
+  m_sifs = sifs;
 }
 
 void 
@@ -252,7 +258,7 @@ DcfManager::GetAccessGrantStart (void) const
   Time rxAccessStart;
   if (m_lastRxEnd >= m_lastRxStart) 
     {
-      rxAccessStart = m_lastRxEnd + m_parameters->GetSifs ();
+      rxAccessStart = m_lastRxEnd + m_sifs;
       if (!m_lastRxReceivedOk)
         {
           /* to handle EIFS */
@@ -261,11 +267,11 @@ DcfManager::GetAccessGrantStart (void) const
     } 
   else 
     {
-      rxAccessStart = m_lastRxStart + m_lastRxDuration + m_parameters->GetSifs ();
+      rxAccessStart = m_lastRxStart + m_lastRxDuration + m_sifs;
     }
-  Time busyAccessStart = m_lastBusyStart + m_lastBusyDuration + m_parameters->GetSifs ();
-  Time txAccessStart = m_lastTxStart + m_lastTxDuration + m_parameters->GetSifs ();
-  Time navAccessStart = m_lastNavStart + m_lastNavDuration + m_parameters->GetSifs ();
+  Time busyAccessStart = m_lastBusyStart + m_lastBusyDuration + m_sifs;
+  Time txAccessStart = m_lastTxStart + m_lastTxDuration + m_sifs;
+  Time navAccessStart = m_lastNavStart + m_lastNavDuration + m_sifs;
   Time accessGrantedStart = MostRecent (rxAccessStart, 
                                         busyAccessStart,
                                         txAccessStart, 
@@ -290,7 +296,7 @@ DcfManager::UpdateBackoff (void)
                                          GetAccessGrantStart ());
       if (mostRecentEvent < Simulator::Now ())
         {
-          Scalar nSlots = (Simulator::Now () - mostRecentEvent) / m_parameters->GetSlotTime ();
+          Scalar nSlots = (Simulator::Now () - mostRecentEvent) / m_slotTime;
           uint32_t nIntSlots = lrint (nSlots.GetDouble ());
           /**
            * For each DcfState, calculate how many backoff slots elapsed since
@@ -332,7 +338,7 @@ DcfManager::DoRestartAccessTimeoutIfNeeded (void)
        * If one of the DcfState needs access to the medium, calculate when its
        * backoff is expected to end.
        */
-      Time expectedBackoffEnd = GetAccessGrantStart () + Scalar (minNSlots) * m_parameters->GetSlotTime ();
+      Time expectedBackoffEnd = GetAccessGrantStart () + Scalar (minNSlots) * m_slotTime;
       NS_LOG_DEBUG ("min n slots=" << minNSlots << ", expected backoff end="<<expectedBackoffEnd);
       /**
        * It is not possible that the backoff was expected to end before now
diff --git a/src/devices/wifi/dcf-manager.h b/src/devices/wifi/dcf-manager.h
index f78b8580b..279571ec9 100644
--- a/src/devices/wifi/dcf-manager.h
+++ b/src/devices/wifi/dcf-manager.h
@@ -49,7 +49,8 @@ class DcfManager
 public:
   DcfManager ();
 
-  void SetParameters (const MacParameters *parameters);
+  void SetSlotTime (Time slotTime);
+  void SetSifs (Time sifs);
 
   // at the lowest mandatory rate.
   // used for EIFS calculation.
@@ -138,7 +139,8 @@ private:
   bool m_sleeping;
   Time m_ackTxTime;
   EventId m_accessTimeout;
-  const MacParameters *m_parameters;
+  Time m_slotTime;
+  Time m_sifs;
 };
 
 } // namespace ns3