diff --git a/src/core/include/mp-units/quantity_point.h b/src/core/include/mp-units/quantity_point.h
index b639ec44..5a4044cf 100644
--- a/src/core/include/mp-units/quantity_point.h
+++ b/src/core/include/mp-units/quantity_point.h
@@ -134,6 +134,7 @@ public:
   quantity_point& operator=(quantity_point&&) = default;
 
   // data access
+  [[nodiscard]] constexpr quantity_type& relative() & noexcept { return q_; }
   [[nodiscard]] constexpr const quantity_type& relative() const& noexcept { return q_; }
   [[nodiscard]] constexpr quantity_type&& relative() && noexcept { return std::move(q_); }
   [[nodiscard]] constexpr const quantity_type&& relative() const&& noexcept { return std::move(q_); }