diff --git a/widget/src/mac/nsWindow.cpp b/widget/src/mac/nsWindow.cpp
index 1059f88a2d0e..fea5cdb8209d 100644
--- a/widget/src/mac/nsWindow.cpp
+++ b/widget/src/mac/nsWindow.cpp
@@ -1824,3 +1824,9 @@ NS_IMETHODIMP nsWindow::CaptureRollupEvents(nsIRollupListener * aListener, PRBoo
 
   return NS_OK;
 }
+
+NS_IMETHODIMP nsWindow::SetTitle(const nsString& title)
+{
+  NS_ASSERTION(0, "Would some Mac person please implement me? Thanks.");
+  return NS_OK;
+}
diff --git a/widget/src/mac/nsWindow.h b/widget/src/mac/nsWindow.h
index e875c657e7e6..63a07732d290 100644
--- a/widget/src/mac/nsWindow.h
+++ b/widget/src/mac/nsWindow.h
@@ -155,6 +155,7 @@ public:
     NS_IMETHOD  			SetCursor(nsCursor aCursor);
     
     NS_IMETHOD         CaptureRollupEvents(nsIRollupListener * aListener, PRBool aDoCapture);
+    NS_IMETHOD        SetTitle(const nsString& title);
   
     // Mac specific methods
     void 					nsRectToMacRect(const nsRect& aRect, Rect& aMacRect) const;