diff --git a/include/rexy/detail/algorithm.hpp b/include/rexy/detail/algorithm.hpp
index 52965ec..edca293 100644
--- a/include/rexy/detail/algorithm.hpp
+++ b/include/rexy/detail/algorithm.hpp
@@ -22,8 +22,7 @@
 #include "../utility.hpp" //swap
 
 #include <type_traits> //nothrow_invocable
-#include <functional> //less, greater
-#include <utility> //pair
+#include <utility> //pair, forward
 #include <iterator> //iterator_traits
 #include <cstddef> //size_t
 
@@ -81,10 +80,15 @@ namespace rexy::detail{
 		}
 		return {max_suffix, period};
 	}
+
 	template<class Iter>
 	constexpr std::pair<std::size_t,size_t> critical_factorization(const Iter& nstart, const Iter& nend){
-		auto msuffix = max_suffix(nstart, nend - nstart, std::less{});
-		auto msuffix_rev = max_suffix(nstart, nend - nstart, std::greater{});
+		auto msuffix = max_suffix(nstart, nend - nstart, []<class T, class U>(T&& left, U&& right) constexpr{
+			return std::forward<T>(left) < std::forward<U>(right);
+		});
+		auto msuffix_rev = max_suffix(nstart, nend - nstart, []<class T, class U>(T&& left, U&& right) constexpr{
+			return std::forward<T>(left) > std::forward<U>(right);
+		});
 		if(msuffix.first < msuffix_rev.first){
 			return msuffix_rev;
 		}