diff --git a/thrust/optional.h b/thrust/optional.h
index 5292e8281..a3fa5b25f 100644
--- a/thrust/optional.h
+++ b/thrust/optional.h
@@ -2089,7 +2089,7 @@ template <class Opt, class F,
                                               *std::declval<Opt>())),
           detail::enable_if_t<std::is_void<Ret>::value> * = nullptr>
 __host__ __device__
-constexpr optional<monostate> optional_map_impl(Opt &&opt, F &&f)
+auto optional_map_impl(Opt &&opt, F &&f) -> optional<monostate>
 {
   if (opt.has_value()) {
     detail::invoke(std::forward<F>(f), *std::forward<Opt>(opt));
diff --git a/thrust/type_traits/integer_sequence.h b/thrust/type_traits/integer_sequence.h
index e33ab9ea3..26ea54213 100644
--- a/thrust/type_traits/integer_sequence.h
+++ b/thrust/type_traits/integer_sequence.h
@@ -98,7 +98,7 @@ template <std::size_t... Is>
 using index_sequence = integer_sequence<std::size_t, Is...>;
 #endif
 
-#if THRUST_CPP_DIALECT >= 2014
+#if THRUST_CPP_DIALECT < 2014
 /*! \cond
  */