diff --git a/src/core/include/units/bits/external/type_list.h b/src/core/include/units/bits/external/type_list.h
index 3eddfcfe..88f52a87 100644
--- a/src/core/include/units/bits/external/type_list.h
+++ b/src/core/include/units/bits/external/type_list.h
@@ -24,6 +24,7 @@
 
 #include <units/bits/external/hacks.h>  // IWYU pragma: keep
 #include <cstddef>
+#include <utility>
 
 UNITS_DIAGNOSTIC_PUSH
 UNITS_DIAGNOSTIC_IGNORE_EXPR_ALWAYS_TF
@@ -47,16 +48,16 @@ concept TypeList = detail::is_type_list<T>;
 
 namespace detail {
 
-template<template<typename...> typename List, typename... Ts>
-consteval std::size_t type_list_size_impl(List<Ts...>)
-{
-  return sizeof...(Ts);
-}
+template<typename List>
+struct type_list_size_impl;
+
+template<template<typename...> typename List, typename... Types>
+struct type_list_size_impl<List<Types...>> : std::integral_constant<std::size_t, sizeof...(Types)> {};
 
 }  // namespace detail
 
 template<TypeList List>
-inline constexpr std::size_t type_list_size = detail::type_list_size_impl(List{});
+inline constexpr std::size_t type_list_size = detail::type_list_size_impl<List>::value;
 
 // front
 
diff --git a/test/unit_test/static/CMakeLists.txt b/test/unit_test/static/CMakeLists.txt
index 5d48f53d..587f824d 100644
--- a/test/unit_test/static/CMakeLists.txt
+++ b/test/unit_test/static/CMakeLists.txt
@@ -53,14 +53,14 @@ add_library(
     # math_test.cpp
     # point_origin_test.cpp
     # prime_test.cpp
-    # ratio_test.cpp
+    ratio_test.cpp
     # references_test.cpp
     # si_test.cpp
     # si_cgs_test.cpp
     # si_fps_test.cpp
     # si_hep_test.cpp
     # symbol_text_test.cpp
-    # type_list_test.cpp
+    type_list_test.cpp
     unit_test.cpp
 
     # us_test.cpp
diff --git a/test/unit_test/static/type_list_test.cpp b/test/unit_test/static/type_list_test.cpp
index 81f39586..81742907 100644
--- a/test/unit_test/static/type_list_test.cpp
+++ b/test/unit_test/static/type_list_test.cpp
@@ -20,10 +20,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
-#include <units/base_dimension.h>
 #include <units/bits/external/type_list.h>
-#include <units/exponent.h>
-#include <units/unit.h>
+#include <units/bits/external/type_traits.h>
 
 namespace {
 
@@ -32,6 +30,29 @@ using namespace units;
 template<typename... Types>
 struct type_list;
 
+// TypeList
+
+static_assert(TypeList<type_list<>>);
+static_assert(TypeList<type_list<int>>);
+static_assert(TypeList<type_list<int, float>>);
+
+// type_list_size
+
+static_assert(type_list_size<type_list<>> == 0);
+static_assert(type_list_size<type_list<int>> == 1);
+static_assert(type_list_size<type_list<int, int>> == 2);
+static_assert(type_list_size<type_list<int, long, int>> == 3);
+
+// type_list_front
+
+template<template<typename...> typename List>
+concept type_list_front_invalid_for_empty_list = !requires { typename type_list_front<List<>>; };
+
+static_assert(type_list_front_invalid_for_empty_list<type_list>);
+static_assert(is_same_v<type_list_front<type_list<int>>, int>);
+static_assert(is_same_v<type_list_front<type_list<long, int>>, long>);
+static_assert(is_same_v<type_list_front<type_list<float, long, int>>, float>);
+
 // type_list_push_front
 
 static_assert(is_same_v<type_list_push_front<type_list<>, int>, type_list<int>>);
@@ -55,6 +76,15 @@ static_assert(
 static_assert(is_same_v<type_list_join<type_list<int, short>, type_list<float, double>, type_list<bool>>,
                         type_list<int, short, float, double, bool>>);
 
+// type_list_join
+static_assert(is_same_v<type_list_join<type_list<>, type_list<>>, type_list<>>);
+static_assert(is_same_v<type_list_join<type_list<int>, type_list<>>, type_list<int>>);
+static_assert(is_same_v<type_list_join<type_list<>, type_list<int>>, type_list<int>>);
+static_assert(is_same_v<type_list_join<type_list<int>, type_list<int>>, type_list<int, int>>);
+static_assert(is_same_v<type_list_join<type_list<int>, type_list<long>>, type_list<int, long>>);
+static_assert(
+  is_same_v<type_list_join<type_list<int, long>, type_list<float, double>>, type_list<int, long, float, double>>);
+
 // type_list_split
 
 static_assert(is_same_v<type_list_split<type_list<int>, 0>::first_list, type_list<>>);
@@ -93,28 +123,46 @@ static_assert(is_same_v<type_list_split_half<type_list<int, long, double, float>
 static_assert(
   is_same_v<type_list_split_half<type_list<int, long, double, float>>::second_list, type_list<double, float>>);
 
-// type_list_merge_sorted
-struct u0 : named_unit<u0, "u0"> {};
-struct d0 : base_dimension<"d0", u0> {};
-struct u1 : named_unit<u1, "u1"> {};
-struct d1 : base_dimension<"d1", u1> {};
+template<auto V>
+struct constant {
+  static constexpr auto value = V;
+};
 
+struct v1 : constant<1> {};
+struct v2 : constant<2> {};
+struct v3 : constant<3> {};
+struct v4 : constant<4> {};
+
+template<typename T1, typename T2>
+struct constant_less : std::bool_constant<(T1::value < T2::value)> {};
+
+// type_list_merge_sorted
+
+static_assert(is_same_v<type_list_merge_sorted<type_list<>, type_list<>, constant_less>, type_list<>>);
+static_assert(is_same_v<type_list_merge_sorted<type_list<v1>, type_list<>, constant_less>, type_list<v1>>);
+static_assert(is_same_v<type_list_merge_sorted<type_list<>, type_list<v1>, constant_less>, type_list<v1>>);
+static_assert(is_same_v<type_list_merge_sorted<type_list<v1>, type_list<v2>, constant_less>, type_list<v1, v2>>);
 static_assert(
-  is_same_v<type_list_merge_sorted<type_list<units::exponent<d0, 1>>, type_list<units::exponent<d1, 1>>, exponent_less>,
-            type_list<units::exponent<d0, 1>, units::exponent<d1, 1>>>);
-static_assert(
-  is_same_v<type_list_merge_sorted<type_list<units::exponent<d1, 1>>, type_list<units::exponent<d0, 1>>, exponent_less>,
-            type_list<units::exponent<d0, 1>, units::exponent<d1, 1>>>);
+  is_same_v<type_list_merge_sorted<type_list<v1, v3>, type_list<v2, v4>, constant_less>, type_list<v1, v2, v3, v4>>);
+static_assert(is_same_v<type_list_merge_sorted<type_list<v1, v2, v3>, type_list<v1, v2, v4>, constant_less>,
+                        type_list<v1, v1, v2, v2, v3, v4>>);
 
 // type_list_sort
 
-template<TypeList List>
-using exp_sort = type_list_sort<List, exponent_less>;
+static_assert(is_same_v<type_list_sort<type_list<>, constant_less>, type_list<>>);
+static_assert(is_same_v<type_list_sort<type_list<v1>, constant_less>, type_list<v1>>);
+static_assert(is_same_v<type_list_sort<type_list<v1, v2>, constant_less>, type_list<v1, v2>>);
+static_assert(is_same_v<type_list_sort<type_list<v2, v1>, constant_less>, type_list<v1, v2>>);
+static_assert(is_same_v<type_list_sort<type_list<v2, v1, v3>, constant_less>, type_list<v1, v2, v3>>);
+static_assert(is_same_v<type_list_sort<type_list<v4, v3, v2, v1>, constant_less>, type_list<v1, v2, v3, v4>>);
 
-static_assert(is_same_v<exp_sort<exponent_list<units::exponent<d0, 1>>>, exponent_list<units::exponent<d0, 1>>>);
-static_assert(is_same_v<exp_sort<exponent_list<units::exponent<d0, 1>, units::exponent<d1, -1>>>,
-                        exponent_list<units::exponent<d0, 1>, units::exponent<d1, -1>>>);
-static_assert(is_same_v<exp_sort<exponent_list<units::exponent<d1, 1>, units::exponent<d0, -1>>>,
-                        exponent_list<units::exponent<d0, -1>, units::exponent<d1, 1>>>);
+// type_list_map
+
+template<typename... Types>
+struct other_list;
+
+static_assert(is_same_v<type_list_map<type_list<>, other_list>, other_list<>>);
+static_assert(is_same_v<type_list_map<type_list<v1>, other_list>, other_list<v1>>);
+static_assert(is_same_v<type_list_map<type_list<v1, v2>, other_list>, other_list<v1, v2>>);
 
 }  // namespace