diff --git a/src/core/include/mp-units/quantity.h b/src/core/include/mp-units/quantity.h
index 23a1f6c3..8f50edfe 100644
--- a/src/core/include/mp-units/quantity.h
+++ b/src/core/include/mp-units/quantity.h
@@ -403,7 +403,7 @@ template<auto R1, typename Rep1, auto R2, typename Rep2>
 }
 
 template<auto R, typename Rep, typename Value>
-  requires(!Quantity<Value>) &&
+  requires(!Quantity<Value>) && (!Reference<Value>) &&
           detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, Rep, const Value&>
 [[nodiscard]] constexpr Quantity auto operator*(const quantity<R, Rep>& q, const Value& v)
 {
@@ -411,7 +411,7 @@ template<auto R, typename Rep, typename Value>
 }
 
 template<typename Value, auto R, typename Rep>
-  requires(!Quantity<Value>) &&
+  requires(!Quantity<Value>) && (!Reference<Value>) &&
           detail::InvokeResultOf<get_quantity_spec(R).character, std::multiplies<>, const Value&, Rep>
 [[nodiscard]] constexpr Quantity auto operator*(const Value& v, const quantity<R, Rep>& q)
 {
@@ -427,7 +427,7 @@ template<auto R1, typename Rep1, auto R2, typename Rep2>
 }
 
 template<auto R, typename Rep, typename Value>
-  requires(!Quantity<Value>) &&
+  requires(!Quantity<Value>) && (!Reference<Value>) &&
           detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, Rep, const Value&>
 [[nodiscard]] constexpr Quantity auto operator/(const quantity<R, Rep>& q, const Value& v)
 {
@@ -436,7 +436,7 @@ template<auto R, typename Rep, typename Value>
 }
 
 template<typename Value, auto R, typename Rep>
-  requires(!Quantity<Value>) &&
+  requires(!Quantity<Value>) && (!Reference<Value>) &&
           detail::InvokeResultOf<get_quantity_spec(R).character, std::divides<>, const Value&, Rep>
 [[nodiscard]] constexpr Quantity auto operator/(const Value& v, const quantity<R, Rep>& q)
 {
diff --git a/src/core/include/mp-units/reference.h b/src/core/include/mp-units/reference.h
index 2a67b64e..204fee55 100644
--- a/src/core/include/mp-units/reference.h
+++ b/src/core/include/mp-units/reference.h
@@ -166,16 +166,14 @@ template<typename Rep, Reference R>
 
 template<typename Q, Reference R>
   requires Quantity<std::remove_cvref_t<Q>>
-[[nodiscard]] constexpr quantity<std::remove_cvref_t<Q>::reference * R{}, typename std::remove_cvref_t<Q>::rep>
-operator*(Q&& q, R)
+[[nodiscard]] constexpr Quantity auto operator*(Q&& q, R)
 {
   return make_quantity<std::remove_cvref_t<Q>::reference * R{}>(std::forward<Q>(q).numerical_value_);
 }
 
 template<typename Q, Reference R>
   requires Quantity<std::remove_cvref_t<Q>>
-[[nodiscard]] constexpr quantity<std::remove_cvref_t<Q>::reference / R{}, typename std::remove_cvref_t<Q>::rep>
-operator/(Q&& q, R)
+[[nodiscard]] constexpr Quantity auto operator/(Q&& q, R)
 {
   return make_quantity<std::remove_cvref_t<Q>::reference / R{}>(std::forward<Q>(q).numerical_value_);
 }