diff --git a/src/osx/nonownedwnd_osx.cpp b/src/osx/nonownedwnd_osx.cpp
index edcba5d9ce..3b6c024958 100644
--- a/src/osx/nonownedwnd_osx.cpp
+++ b/src/osx/nonownedwnd_osx.cpp
@@ -307,7 +307,7 @@ void wxNonOwnedWindow::HandleActivated( double timestampsec, bool didActivate )
     HandleWindowEvent(wxevent);
 }
 
-void wxNonOwnedWindow::HandleResized( double timestampsec )
+void wxNonOwnedWindow::HandleResized( double WXUNUSED(timestampsec) )
 {
     SendSizeEvent();
     // we have to inform some controls that have to reset things