diff --git a/src/core/include/mp-units/quantity.h b/src/core/include/mp-units/quantity.h
index 6579a5c0..ff1dc9b1 100644
--- a/src/core/include/mp-units/quantity.h
+++ b/src/core/include/mp-units/quantity.h
@@ -47,9 +47,9 @@ template<QuantityLike Q>
 using quantity_like_type = quantity<quantity_like_traits<Q>::reference, typename quantity_like_traits<Q>::rep>;
 
 template<typename T, typename Arg, auto U>
-concept RepSafeConstructibleFrom =
-  Unit<std::remove_const_t<decltype(U)>> && std::constructible_from<T, Arg> &&
-  (treat_as_floating_point<T> || (!treat_as_floating_point<Arg> && is_rational(get_canonical_unit(U).mag)));
+concept RepSafeConstructibleFrom = Unit<std::remove_const_t<decltype(U)>> && std::constructible_from<T, Arg> &&
+                                   (treat_as_floating_point<T> || (!treat_as_floating_point<std::remove_cvref_t<Arg>> &&
+                                                                   is_rational(get_canonical_unit(U).mag)));
 
 template<auto UFrom, auto UTo>
 concept IntegralConversionFactor = Unit<decltype(UFrom)> && Unit<decltype(UTo)> &&