diff --git a/ThirdParty/phys/units/quantity.hpp b/ThirdParty/phys/units/quantity.hpp
index 06fbb4b2c760dfc8641d58392aa30062ff7c4e84..970773d598ec4e076467fb990c9fdb610b9c936f 100644
--- a/ThirdParty/phys/units/quantity.hpp
+++ b/ThirdParty/phys/units/quantity.hpp
@@ -473,6 +473,16 @@ namespace phys {
       friend constexpr bool operator>=(quantity<D, X> const& x, quantity<D, Y> const& y);
     };
 
+    // helper to check whether some type is a quantity
+    template <typename TNonQuantityType>
+    struct is_quantity : std::false_type {};
+
+    template <typename Dims, typename T>
+    struct is_quantity<quantity<Dims, T>> : std::true_type {};
+
+    template <typename T>
+    constexpr bool is_quantity_v = is_quantity<T>::value;
+
     // Give names to the seven fundamental dimensions of physical reality.
 
     typedef dimensions<1, 0, 0, 0, 0, 0, 0, 0> length_d;