diff --git a/src/sugar/graphics/radiotoolbutton.py b/src/sugar/graphics/radiotoolbutton.py
index 001ed068..abdf54ce 100644
--- a/src/sugar/graphics/radiotoolbutton.py
+++ b/src/sugar/graphics/radiotoolbutton.py
@@ -89,7 +89,7 @@ class RadioToolButton(gtk.RadioToolButton):
     def get_xo_color(self):
         return self._xo_color
 
-    xo_color = gobject.property(type=str, setter=set_xo_color,
+    xo_color = gobject.property(type=object, setter=set_xo_color,
                                 getter=get_xo_color)
 
     def create_palette(self):