--- a/glib/glibmm/threads.h	
+++ a/glib/glibmm/threads.h	
@@ -657,7 +657,7 @@ public:
    */
   inline void replace(T* data);
 
-  GPrivate* gobj() { return gobject_; }
+  GPrivate* gobj() { return &gobject_; }
 
 private:
   GPrivate gobject_;