diff --git a/src/gnatcoll_gtk.gpr b/src/gnatcoll_gtk.gpr
index f37017df..6654804d 100644
--- a/src/gnatcoll_gtk.gpr
+++ b/src/gnatcoll_gtk.gpr
@@ -71,7 +71,7 @@ project GnatColl_Gtk is
       for Switches ("Ada") use GnatColl_Shared.Compiler'Switches ("Ada");
 
       for Switches ("C") use
-        ("-g", "-O2")
+        ("-g", "-O2", "-fPIC")
         & GnatColl_Shared.Python_Cflags
         & GnatColl_Shared.Pygtk_Include
         & GnatColl_Shared.PyGobject_Include