diff --git a/src/core/include/mp-units/framework/magnitude.h b/src/core/include/mp-units/framework/magnitude.h
index db0c2af6..32fdd81d 100644
--- a/src/core/include/mp-units/framework/magnitude.h
+++ b/src/core/include/mp-units/framework/magnitude.h
@@ -589,6 +589,8 @@ struct pi : mag_constant {
 };
 inline constexpr pi pi;
 
+[[deprecated("Use `mag<pi>` instead")]] inline constexpr Magnitude auto mag_pi = mag<pi>;
+
 MP_UNITS_EXPORT_END
 
 namespace detail {