Const references?

This line:

#define NEW_PTR_PARAM_DECL(z, n, _) BOOST_PP_COMMA_IF(n) A ## n const & a ## n

Has the 'const' keyword, making it so that const references are always passed to the class's constructor. But my class's constructor has one parameter that is a non-const reference. If I comment the const part it works. Maybe should edit the recipe?