diff --git a/src/a2functional.h b/src/a2functional.h
index c1059fef..8c8a18ba 100644
--- a/src/a2functional.h
+++ b/src/a2functional.h
@@ -103,7 +103,7 @@ std::string strjoin(InputIterator first, InputIterator last,
 }
 
 template <typename T>
-class LeastRecentAccess : public std::binary_function<T, T, bool> {
+class LeastRecentAccess {
 public:
   bool operator()(const std::shared_ptr<T>& lhs,
                   const std::shared_ptr<T>& rhs) const