diff --git a/src/wifi/model/wifi-information-element.cc b/src/wifi/model/wifi-information-element.cc
index c5bfb9752..05a338aeb 100644
--- a/src/wifi/model/wifi-information-element.cc
+++ b/src/wifi/model/wifi-information-element.cc
@@ -55,6 +55,9 @@ WifiInformationElement::Deserialize (Buffer::Iterator i)
   // This IE was not optional, so confirm that we did actually
   // deserialise something.
   NS_ASSERT (i.GetDistanceFrom (start) != 0);
+  // cast start to void, to suppress ‘start’ set but not used
+  // compiler warning in optimized builds
+  (void) start;
   return i;
 }
 
diff --git a/src/wifi/model/wifi-remote-station-manager.cc b/src/wifi/model/wifi-remote-station-manager.cc
index 44afd76cc..60c430201 100644
--- a/src/wifi/model/wifi-remote-station-manager.cc
+++ b/src/wifi/model/wifi-remote-station-manager.cc
@@ -368,6 +368,9 @@ WifiRemoteStationManager::GetDataMode (Mac48Address address, const WifiMacHeader
       bool found;
       found = ConstCast<Packet> (packet)->PeekPacketTag (tag);
       NS_ASSERT (found);
+      // cast found to void, to suppress 'found' set but not used
+      // compiler warning
+      (void) found;
       return tag.GetDataMode ();
     }
   return DoGetDataMode (Lookup (address, header), fullPacketSize);
@@ -383,6 +386,9 @@ WifiRemoteStationManager::GetRtsMode (Mac48Address address, const WifiMacHeader
       bool found;
       found = ConstCast<Packet> (packet)->PeekPacketTag (tag);
       NS_ASSERT (found);
+      // cast found to void, to suppress 'found' set but not used
+      // compiler warning
+      (void) found;
       return tag.GetRtsMode ();
     }
   return DoGetRtsMode (Lookup (address, header));