diff --git a/include/boost/detail/sp_counted_base_w32.hpp b/include/boost/detail/sp_counted_base_w32.hpp
index 273a07f..e84f06e 100644
--- a/include/boost/detail/sp_counted_base_w32.hpp
+++ b/include/boost/detail/sp_counted_base_w32.hpp
@@ -20,6 +20,9 @@
 //
 //  Lock-free algorithm by Alexander Terekhov
 //
+//  Thanks to Ben Hitchings for the #weak + (#shared != 0)
+//  formulation
+//
 
 #include <boost/detail/interlocked.hpp>
 #include <typeinfo>