Index: pthread/tss.hpp
===================================================================
--- pthread/tss.hpp	(revision 45823)
+++ pthread/tss.hpp	(working copy)
@@ -56,7 +56,15 @@
             }
         };
 
+        struct noop_cleanup_function:
+            detail::tss_cleanup_function
+        {
+            void operator()(void*)
+            {
+            }
+        };
 
+
         boost::shared_ptr<detail::tss_cleanup_function> cleanup;
         
     public:
@@ -64,7 +72,9 @@
             cleanup(new delete_data)
         {}
         explicit thread_specific_ptr(void (*func_)(T*)):
-            cleanup(new run_custom_cleanup_function(func_))
+            cleanup(func_ ?
+                    static_cast<detail::tss_cleanup_function*>(new run_custom_cleanup_function(func_)) :
+                    static_cast<detail::tss_cleanup_function*>(new noop_cleanup_function))
         {}
         ~thread_specific_ptr()
         {
Index: win32/tss.hpp
===================================================================
--- win32/tss.hpp	(revision 45823)
+++ win32/tss.hpp	(working copy)
@@ -51,7 +51,7 @@
             
             void operator()(void* data)
             {
-                cleanup_function(static_cast<T*>(data));
+                if (cleanup_function) cleanup_function(static_cast<T*>(data));
             }
         };