diff --git a/src/wifi/model/txop.cc b/src/wifi/model/txop.cc
index 924562de3..df246eabb 100644
--- a/src/wifi/model/txop.cc
+++ b/src/wifi/model/txop.cc
@@ -59,7 +59,7 @@ Txop::GetTypeId (void)
                    UintegerValue (2),
                    MakeUintegerAccessor (&Txop::SetAifsn,
                                          &Txop::GetAifsn),
-                   MakeUintegerChecker<uint32_t> ())
+                   MakeUintegerChecker<uint8_t> ())
     .AddAttribute ("TxopLimit", "The TXOP limit: the default value conforms to non-QoS.",
                    TimeValue (MilliSeconds (0)),
                    MakeTimeAccessor (&Txop::SetTxopLimit,
@@ -253,9 +253,9 @@ Txop::StartBackoffNow (uint32_t nSlots)
 }
 
 void
-Txop::SetAifsn (uint32_t aifsn)
+Txop::SetAifsn (uint8_t aifsn)
 {
-  NS_LOG_FUNCTION (this << aifsn);
+  NS_LOG_FUNCTION (this << +aifsn);
   m_aifsn = aifsn;
 }
 
@@ -279,7 +279,7 @@ Txop::GetMaxCw (void) const
   return m_cwMax;
 }
 
-uint32_t
+uint8_t
 Txop::GetAifsn (void) const
 {
   return m_aifsn;
diff --git a/src/wifi/model/txop.h b/src/wifi/model/txop.h
index b21db2f34..66368b82f 100644
--- a/src/wifi/model/txop.h
+++ b/src/wifi/model/txop.h
@@ -173,7 +173,7 @@ public:
    *
    * \param aifsn the number of slots that make up an AIFS.
    */
-  void SetAifsn (uint32_t aifsn);
+  void SetAifsn (uint8_t aifsn);
   /**
    * Set the TXOP limit.
    *
@@ -198,7 +198,7 @@ public:
    *
    * \return the number of slots that make up an AIFS.
    */
-  uint32_t GetAifsn (void) const;
+  uint8_t GetAifsn (void) const;
   /**
    * Return the TXOP limit.
    *
@@ -515,7 +515,7 @@ protected:
    */
   Time m_backoffStart;
 
-  uint32_t m_aifsn;        //!< the AIFSN
+  uint8_t m_aifsn;        //!< the AIFSN
   Time m_txopLimit;       //!< the txop limit time
 
   Ptr<const Packet> m_currentPacket; //!< the current packet