--- sigc++/functors/slot_base.h	2008-02-26 22:44:34.000000000 +0300
+++ sigc++/functors/slot_base.h	2009-02-27 14:14:38.000000000 +0300
@@ -232,7 +232,7 @@
    */
   slot_base(const slot_base& src);
 
-  ~slot_base();
+  virtual ~slot_base();
 
   /** Tests whether a slot is null, because the default constructor was used.
    * Test a slot for null like so:
