diff --git a/example/example.cpp b/example/example.cpp
index ef262987..27685ce1 100644
--- a/example/example.cpp
+++ b/example/example.cpp
@@ -46,7 +46,7 @@ void example_2(double distance_v, double duration_v)
 {
   stde::units::quantity<stde::units::kilometre> distance(distance_v);
   stde::units::quantity<stde::units::hour> duration(duration_v);
-  const auto kmph = avg_speed(distance, duration);
+  const auto kmph = quantity_cast<stde::units::kilometre_per_hour>(avg_speed(distance, duration));
   std::cout << "Average speed of a car that makes " << distance.count() << " km in "
             << duration.count() << " hours is " << kmph.count() << " km/h.\n";
 }
diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index 5886914f..321c0ad7 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -135,6 +135,13 @@ namespace std::experimental::units {
     return cast::cast(q);
   }
 
+  template<Unit ToU, Scalar ToRep = double, typename U, typename Rep>
+  constexpr quantity<ToU, ToRep> quantity_cast(const quantity<U, Rep>& q)
+  {
+    return quantity_cast<quantity<ToU, ToRep>>(q);
+  }
+
+
   // quantity_values
 
   template<Scalar Rep>