diff --git a/src/core/include/mp-units/framework/reference_concepts.h b/src/core/include/mp-units/framework/reference_concepts.h
index 798e9411..0bd2a49d 100644
--- a/src/core/include/mp-units/framework/reference_concepts.h
+++ b/src/core/include/mp-units/framework/reference_concepts.h
@@ -91,17 +91,21 @@ struct absolute_ final {
   static constexpr Reference auto _original_reference_ = R{};
 };
 
-template<Reference auto R>
-MP_UNITS_EXPORT inline constexpr relative_<MP_UNITS_REMOVE_CONST(decltype(R))> delta{};
+MP_UNITS_EXPORT_BEGIN
 
 template<Reference auto R>
-MP_UNITS_EXPORT inline constexpr absolute_<MP_UNITS_REMOVE_CONST(decltype(R))> absolute{};
+inline constexpr relative_<MP_UNITS_REMOVE_CONST(decltype(R))> delta{};
+
+template<Reference auto R>
+inline constexpr absolute_<MP_UNITS_REMOVE_CONST(decltype(R))> absolute{};
 
 template<typename T>
-MP_UNITS_EXPORT concept DeltaReference =
+concept DeltaReference =
   (Reference<T> && !requires { get_unit(T{}).point_origin; }) || is_specialization_of<T, relative_>;
 
 template<typename T>
-MP_UNITS_EXPORT concept AbsoluteReference = is_specialization_of<T, absolute_>;
+concept AbsoluteReference = is_specialization_of<T, absolute_>;
+
+MP_UNITS_EXPORT_END
 
 }  // namespace mp_units