diff --git a/layout/html/forms/src/nsGfxTextControlFrame.h b/layout/html/forms/src/nsGfxTextControlFrame.h
index 5d728ca26c40..2165190e7b4d 100644
--- a/layout/html/forms/src/nsGfxTextControlFrame.h
+++ b/layout/html/forms/src/nsGfxTextControlFrame.h
@@ -487,6 +487,8 @@ protected:
 
   PRBool IsInitialized() const;
 
+  PRInt32 GetWidthInCharacters() const;
+
 
 protected:
   nsIWebShell* mWebShell;