diff --git a/widget/src/gtk/nsWindow.cpp b/widget/src/gtk/nsWindow.cpp
index 688981dd0816..1fe198a2ce89 100644
--- a/widget/src/gtk/nsWindow.cpp
+++ b/widget/src/gtk/nsWindow.cpp
@@ -822,7 +822,7 @@ nsWindow::OnDrawSignal(GdkRectangle * aArea)
 // Add an XATOM property to this window.
 // Assuming XA_STRING type.
 // Borrowed from xfe classic branch.
-void nsWindow::StoreProperty(char *property, const unsigned char *data)
+void nsWindow::StoreProperty(char *property, unsigned char *data)
 {
   
   // This needs to happen before properties start working.
diff --git a/widget/src/gtk/nsWindow.h b/widget/src/gtk/nsWindow.h
index fe9dbd447cb8..b051c701f78b 100644
--- a/widget/src/gtk/nsWindow.h
+++ b/widget/src/gtk/nsWindow.h
@@ -67,7 +67,7 @@ public:
   gint                 ConvertBorderStyles(nsBorderStyle bs);
 
   // Add an XATOM property to this window.
-  void                 StoreProperty(char *property, const unsigned char *data);
+  void                 StoreProperty(char *property, unsigned char *data);
 
   virtual PRBool IsChild() const;