diff --git a/include/boost/functional/overloaded_function/detail/base.hpp b/include/boost/functional/overloaded_function/detail/base.hpp
index 8c1d4bf..8fd9a0a 100644
--- a/include/boost/functional/overloaded_function/detail/base.hpp
+++ b/include/boost/functional/overloaded_function/detail/base.hpp
@@ -33,6 +33,7 @@
     R (BOOST_PP_ENUM(BOOST_FUNCTIONAL_DETAIL_arity, \
             BOOST_FUNCTIONAL_DETAIL_arg_type, ~))
 
+// Do not use namespace ::detail because overloaded_function is already a class.
 namespace boost { namespace overloaded_function_detail {
 
 template<typename F>
diff --git a/include/boost/functional/overloaded_function/detail/function_type.hpp b/include/boost/functional/overloaded_function/detail/function_type.hpp
index 4494206..4169ee9 100644
--- a/include/boost/functional/overloaded_function/detail/function_type.hpp
+++ b/include/boost/functional/overloaded_function/detail/function_type.hpp
@@ -22,6 +22,7 @@
 #include <boost/mpl/push_front.hpp>
 #include <boost/typeof/typeof.hpp>
 
+// Do not use namespace ::detail because overloaded_function is already a class.
 namespace boost { namespace overloaded_function_detail {
 
 // Requires: F is a monomorphic functor (i.e., has non-template `operator()`).