diff --git a/src/core/include/mp-units/bits/dimension_concepts.h b/src/core/include/mp-units/bits/dimension_concepts.h
index 5a5991e4..770c0f7b 100644
--- a/src/core/include/mp-units/bits/dimension_concepts.h
+++ b/src/core/include/mp-units/bits/dimension_concepts.h
@@ -85,11 +85,11 @@ namespace detail {
 /**
  * @brief A concept matching all derived dimensions in the library.
  *
- * Satisfied by all dimension types either being a specialization of `derived_dimension`
- * or derived from it (inheritance needed to properly handle `dimension_one`).
+ * Satisfied by all dimension types being a specialization of `derived_dimension` or
+ * being the `dimension_one`.
  */
 template<typename T>
-concept DerivedDimension = is_derived_from_specialization_of<T, derived_dimension>;
+concept DerivedDimension = is_specialization_of<T, derived_dimension> || is_dimension_one<T>::value;
 
 }  // namespace detail
 
diff --git a/src/core/include/mp-units/dimension.h b/src/core/include/mp-units/dimension.h
index a0a4dc8b..f04d7363 100644
--- a/src/core/include/mp-units/dimension.h
+++ b/src/core/include/mp-units/dimension.h
@@ -153,7 +153,7 @@ template<Dimension Lhs, Dimension Rhs>
 template<Dimension Lhs, Dimension Rhs>
 [[nodiscard]] consteval bool operator==(Lhs, Rhs)
 {
-  return is_same_v<Lhs, Rhs>;
+  return std::derived_from<Lhs, Rhs> || std::derived_from<Rhs, Lhs>;
 }
 
 [[nodiscard]] consteval Dimension auto inverse(Dimension auto d) { return dimension_one / d; }
diff --git a/test/unit_test/static/concepts_test.cpp b/test/unit_test/static/concepts_test.cpp
index b63228b0..978e1356 100644
--- a/test/unit_test/static/concepts_test.cpp
+++ b/test/unit_test/static/concepts_test.cpp
@@ -61,8 +61,8 @@ static_assert(detail::DerivedDimension<std::remove_const_t<decltype(isq::dim_len
 static_assert(detail::DerivedDimension<std::remove_const_t<decltype(inverse(isq::dim_time))>>);
 static_assert(detail::DerivedDimension<std::remove_const_t<decltype(pow<2>(isq::dim_length))>>);
 static_assert(detail::DerivedDimension<derived_dimension<struct isq::dim_length, per<struct isq::dim_time>>>);
-static_assert(detail::DerivedDimension<dim_speed>);
 static_assert(detail::DerivedDimension<struct dimension_one>);
+static_assert(!detail::DerivedDimension<dim_speed>);
 static_assert(!detail::DerivedDimension<struct isq::dim_length>);
 static_assert(!detail::DerivedDimension<struct si::metre>);
 static_assert(!detail::DerivedDimension<int>);
@@ -73,8 +73,8 @@ static_assert(Dimension<std::remove_const_t<decltype(isq::dim_length / isq::dim_
 static_assert(Dimension<std::remove_const_t<decltype(inverse(isq::dim_time))>>);
 static_assert(Dimension<std::remove_const_t<decltype(pow<2>(isq::dim_length))>>);
 static_assert(Dimension<derived_dimension<struct isq::dim_length, per<struct isq::dim_time>>>);
-static_assert(Dimension<dim_speed>);
 static_assert(Dimension<struct dimension_one>);
+static_assert(!Dimension<dim_speed>);
 static_assert(!Dimension<base_dimension<"L">>);
 static_assert(!Dimension<struct si::metre>);
 static_assert(!Dimension<int>);