diff --git a/src/wifi/model/dcf-manager.cc b/src/wifi/model/dcf-manager.cc
index 20899063e..96a4659b9 100644
--- a/src/wifi/model/dcf-manager.cc
+++ b/src/wifi/model/dcf-manager.cc
@@ -493,6 +493,12 @@ DcfManager::IsBusy (void) const
     {
       return true;
     }
+  // CCA busy
+  Time lastCCABusyEnd = m_lastBusyStart + m_lastBusyDuration;
+  if (lastCCABusyEnd > Simulator::Now ())
+    {
+      return true;
+    }
   return false;
 }
 
diff --git a/src/wifi/model/dcf-manager.h b/src/wifi/model/dcf-manager.h
index 22641df4b..900f7108f 100644
--- a/src/wifi/model/dcf-manager.h
+++ b/src/wifi/model/dcf-manager.h
@@ -529,7 +529,7 @@ private:
   void DoGrantAccess (void);
   /**
    * Check if the device is busy sending or receiving,
-   * or NAV busy.
+   * or NAV or CCA busy.
    *
    * \return true if the device is busy,
    *         false otherwise
diff --git a/src/wifi/test/dcf-manager-test.cc b/src/wifi/test/dcf-manager-test.cc
index ed6c625b6..043ecec56 100644
--- a/src/wifi/test/dcf-manager-test.cc
+++ b/src/wifi/test/dcf-manager-test.cc
@@ -623,8 +623,8 @@ DcfManagerTest::DoRun (void)
   AddAccessRequest (21, 1, 24, 0);
   EndTest ();
 
-  //  20          40       50     53      54   55
-  //   | switching |  busy  | sifs | aifsn | tx |
+  //  20          40       50     53      54       55        56   57
+  //   | switching |  busy  | sifs | aifsn | bslot0 | bslot 1 | tx | 
   //         |          |
   //        30 busy.   45 access request.
   //
@@ -632,7 +632,8 @@ DcfManagerTest::DoRun (void)
   AddDcfState (1);
   AddSwitchingEvt (20,20);
   AddCcaBusyEvt (30,20);
-  AddAccessRequest (45, 1, 54, 0);
+  ExpectCollision (45, 2, 0); //backoff: 2 slots
+  AddAccessRequest (45, 1, 56, 0);
   EndTest ();
 
   //  20     30          50     53      54   55