diff --git a/include/continuable/detail/container-category.hpp b/include/continuable/detail/container-category.hpp
index 359315c..2aea4c4 100644
--- a/include/continuable/detail/container-category.hpp
+++ b/include/continuable/detail/container-category.hpp
@@ -31,8 +31,6 @@
 #ifndef CONTINUABLE_DETAIL_CONTAINER_CATEGORY_HPP_INCLUDED
 #define CONTINUABLE_DETAIL_CONTAINER_CATEGORY_HPP_INCLUDED
 
-#include <continuable/continuable-api.hpp>
-
 namespace cti {
 namespace detail {
 namespace traversal {
diff --git a/include/continuable/detail/traits.hpp b/include/continuable/detail/traits.hpp
index 842a240..9ea0c10 100644
--- a/include/continuable/detail/traits.hpp
+++ b/include/continuable/detail/traits.hpp
@@ -408,6 +408,35 @@ constexpr auto merge(identity<LeftArgs...> /*left*/,
                std::forward<Rest>(rest)...);
 }
 
+namespace detail {
+template <typename T, typename Args, typename = traits::void_t<>>
+struct is_invokable_impl : std::common_type<std::false_type> {};
+
+template <typename T, typename... Args>
+struct is_invokable_impl<
+    T, std::tuple<Args...>,
+    void_t<decltype(std::declval<T>()(std::declval<Args>()...))>>
+    : std::common_type<std::true_type> {};
+} // namespace detail
+
+/// Deduces to a std::true_type if the given type is callable with the arguments
+/// inside the given tuple.
+/// The main reason for implementing it with the detection idiom instead of
+/// hana like detection is that MSVC has issues with capturing raw template
+/// arguments inside lambda closures.
+///
+/// ```cpp
+/// traits::is_invokable<object, std::tuple<Args...>>
+/// ```
+template <typename T, typename Args>
+using is_invokable_from_tuple =
+    typename detail::is_invokable_impl<T, Args>::type;
+
+// Checks whether the given callable object is invocable with the given
+// arguments. This doesn't take member functions into account!
+template <typename T, typename... Args>
+using is_invocable = is_invokable_from_tuple<T, std::tuple<Args...>>;
+
 /// Deduces to a std::false_type
 template <typename T>
 using fail = std::integral_constant<bool, !std::is_same<T, T>::value>;
@@ -415,6 +444,7 @@ using fail = std::integral_constant<bool, !std::is_same<T, T>::value>;
 #ifdef CONTINUABLE_HAS_CXX17_DISJUNCTION
 using std::disjunction;
 #else
+namespace detail {
 /// Declares a C++14 polyfill for C++17 std::disjunction.
 template <typename Args, typename = void_t<>>
 struct disjunction_impl : std::common_type<std::false_type> {};
@@ -422,8 +452,10 @@ template <typename... Args>
 struct disjunction_impl<identity<Args...>,
                         void_t<std::enable_if_t<bool(Args::value)>...>>
     : std::common_type<std::true_type> {};
+} // namespace detail
+
 template <typename... Args>
-using disjunction = disjunction_impl<identity<Args...>>;
+using disjunction = typename detail::disjunction_impl<identity<Args...>>::type;
 #endif // CONTINUABLE_HAS_CXX17_DISJUNCTION
 
 } // namespace traits
diff --git a/include/continuable/detail/traverse.hpp b/include/continuable/detail/traverse.hpp
index 823a2b4..fdc1522 100644
--- a/include/continuable/detail/traverse.hpp
+++ b/include/continuable/detail/traverse.hpp
@@ -304,7 +304,8 @@ template <typename T, typename E, typename = void>
 struct has_push_back : std::false_type {};
 template <typename T, typename E>
 struct has_push_back<
-    T, E, std::void_t<decltype(std::declval<T>().push_back(std::declval<E>()))>>
+    T, E,
+    traits::void_t<decltype(std::declval<T>().push_back(std::declval<E>()))>>
     : std::true_type {};
 
 /// Specialization for a container with a single type T
@@ -554,7 +555,7 @@ struct tuple_like_remapper<strategy_traverse_tag, M, Base<OldArgs...>,
 
   template <typename... Args>
   auto operator()(Args&&... args)
-      -> std::void_t<typename invoke_result<M, OldArgs>::type...> {
+      -> traits::void_t<typename invoke_result<M, OldArgs>::type...> {
     int dummy[] = {0, ((void)mapper_(std::forward<Args>(args)), 0)...};
     (void)dummy;
   }
diff --git a/include/continuable/detail/util.hpp b/include/continuable/detail/util.hpp
index 452cad0..81fb45a 100644
--- a/include/continuable/detail/util.hpp
+++ b/include/continuable/detail/util.hpp
@@ -48,29 +48,6 @@ template <typename... T>
 void unused(T&&...) {
 }
 
-namespace detail {
-template <typename T, typename Args, typename = traits::void_t<>>
-struct is_invokable_impl : std::common_type<std::false_type> {};
-
-template <typename T, typename... Args>
-struct is_invokable_impl<
-    T, std::tuple<Args...>,
-    traits::void_t<decltype(std::declval<T>()(std::declval<Args>()...))>>
-    : std::common_type<std::true_type> {};
-} // namespace detail
-
-/// Deduces to a std::true_type if the given type is callable with the arguments
-/// inside the given tuple.
-/// The main reason for implementing it with the detection idiom instead of
-/// hana like detection is that MSVC has issues with capturing raw template
-/// arguments inside lambda closures.
-///
-/// ```cpp
-/// traits::is_invokable<object, std::tuple<Args...>>
-/// ```
-template <typename T, typename Args>
-using is_invokable = typename detail::is_invokable_impl<T, Args>::type;
-
 namespace detail {
 /// Forwards every element in the tuple except the last one
 template <typename T>
@@ -117,7 +94,8 @@ auto partial_invoke_impl(std::false_type, T&& callable,
   auto next = forward_except_last(std::move(args));
 
   // Test whether we are able to call the function with the given tuple
-  is_invokable<decltype(callable), decltype(next)> is_invokable;
+  traits::is_invokable_from_tuple<decltype(callable), decltype(next)>
+      is_invokable;
 
   return partial_invoke_impl(is_invokable, std::forward<T>(callable),
                              std::move(next));
@@ -150,7 +128,8 @@ auto partial_invoke_impl_shortcut(std::false_type failed, T&& callable,
 template <typename T, typename... Args>
 /*keep this inline*/ inline auto partial_invoke(T&& callable, Args&&... args) {
   // Test whether we are able to call the function with the given arguments.
-  is_invokable<decltype(callable), std::tuple<Args...>> is_invokable;
+  traits::is_invokable_from_tuple<decltype(callable), std::tuple<Args...>>
+      is_invokable;
 
   // The implementation is done in a shortcut way so there are less
   // type instantiations needed to call the callable with its full signature.