diff --git a/include/boost/integer.hpp b/include/boost/integer.hpp
index a5ef737..058a905 100644
--- a/include/boost/integer.hpp
+++ b/include/boost/integer.hpp
@@ -31,6 +31,7 @@ namespace boost
 
   //  specializatons: 1=long, 2=int, 3=short, 4=signed char,
   //     6=unsigned long, 7=unsigned int, 8=unsigned short, 9=unsigned long
+  //  no specializations for 0 and 5: requests for a type > long are in error
   template<> struct int_least_helper<1> { typedef long least; };
   template<> struct int_least_helper<2> { typedef int least; };
   template<> struct int_least_helper<3> { typedef short least; };