diff --git a/include/continuable/detail/traverse.hpp b/include/continuable/detail/traverse.hpp
index 4d2f98a..3d736fc 100644
--- a/include/continuable/detail/traverse.hpp
+++ b/include/continuable/detail/traverse.hpp
@@ -284,11 +284,17 @@ struct strategy_remap_tag {};
 template <typename Mapper, typename T>
 using is_effective_t = traits::is_invocable<typename Mapper::traversor_type, T>;
 
+// TODO find out whether the linear compile-time instantiation is faster:
+// template <typename Mapper, typename... T>
+// struct is_effective_any_of_t
+//     : traits::disjunction<is_effective_t<Mapper, T>...> {};
+// template <typename Mapper>
+// struct is_effective_any_of_t<Mapper> : std::false_type {};
+
 /// Deduces to a true type if any type leads to at least one effective
 /// call to the mapper.
 template <typename Mapper, typename... T>
 struct is_effective_any_of_t;
-
 template <typename Mapper, typename First, typename... Rest>
 struct is_effective_any_of_t<Mapper, First, Rest...>
     : std::conditional<is_effective_t<Mapper, First>::value, std::true_type,
diff --git a/test/unit-test/single/test-continuable-traverse.cpp b/test/unit-test/single/test-continuable-traverse.cpp
index d656794..2fa853e 100644
--- a/test/unit-test/single/test-continuable-traverse.cpp
+++ b/test/unit-test/single/test-continuable-traverse.cpp
@@ -548,7 +548,7 @@ TEST(test_strategic_container_traverse, traverse_move_only_wrapped) {
 
   std::size_t counter = 0;
   traverse_pack(
-      [&counter](auto&& ptr) {
+      [&counter](auto&& ptr) -> void {
         auto moved(std::forward<decltype(ptr)>(ptr));
         EXPECT_EQ((*moved), 5);
         ++counter;