diff --git a/src/core/include/units/quantity_kind.h b/src/core/include/units/quantity_kind.h
index ada8a83a..be3f01ad 100644
--- a/src/core/include/units/quantity_kind.h
+++ b/src/core/include/units/quantity_kind.h
@@ -83,6 +83,7 @@ public:
   using dimension = typename quantity_type::dimension;
   using unit = typename quantity_type::unit;
   using rep = typename quantity_type::rep;
+  static constexpr units::reference<D, U> reference{};
 
 private:
   quantity_type q_;
diff --git a/src/core/include/units/quantity_point.h b/src/core/include/units/quantity_point.h
index e735ff37..77d4e422 100644
--- a/src/core/include/units/quantity_point.h
+++ b/src/core/include/units/quantity_point.h
@@ -49,6 +49,7 @@ public:
   using dimension = typename quantity_type::dimension;
   using unit = typename quantity_type::unit;
   using rep = typename quantity_type::rep;
+  static constexpr units::reference<D, U> reference{};
 
 private:
   quantity_type q_{};
diff --git a/src/core/include/units/quantity_point_kind.h b/src/core/include/units/quantity_point_kind.h
index 04fb9ed6..f2d2d716 100644
--- a/src/core/include/units/quantity_point_kind.h
+++ b/src/core/include/units/quantity_point_kind.h
@@ -50,6 +50,7 @@ public:
   using dimension = typename quantity_type::dimension;
   using unit = typename quantity_type::unit;
   using rep = typename quantity_type::rep;
+  static constexpr units::reference<D, U> reference{};
 
 private:
   quantity_kind_type qk_;