diff --git a/example/ex2/ex2.cpp b/example/ex2/ex2.cpp
index af2e80dd..97d32e0f 100644
--- a/example/ex2/ex2.cpp
+++ b/example/ex2/ex2.cpp
@@ -9,6 +9,7 @@ main () {
     namespace q = xo::qty::qty;
     namespace su = xo::qty::su;
     using xo::qty::with_units_from;
+    using xo::qty::with_units;
     using xo::qty::quantity;
     using xo::flatstring;
     using namespace std;
@@ -30,12 +31,18 @@ main () {
 
     cerr << "a2: " << a2 << endl;
 
-    constexpr auto au = q::meter / (q::second * q::second);
-    constexpr auto a3 = with_units_from(a, au);
+    constexpr auto a3 = with_units<su::meter / (su::second * su::second)>(a);
 
     static_assert(a3.abbrev() == flatstring("m.s^-2"));
 
     cerr << "a3: " << a3 << endl;
+
+    constexpr auto au = q::meter / (q::second * q::second);
+    constexpr auto a4 = with_units_from(a, au);
+
+    static_assert(a4.abbrev() == flatstring("m.s^-2"));
+
+    cerr << "a4: " << a4 << endl;
 }
 
 
diff --git a/include/xo/unit/quantity.hpp b/include/xo/unit/quantity.hpp
index 68fae4fe..2eff0adf 100644
--- a/include/xo/unit/quantity.hpp
+++ b/include/xo/unit/quantity.hpp
@@ -227,6 +227,14 @@ namespace xo {
             };
         } /*namespace detail*/
 
+        template <auto Unit, typename Q1>
+        requires(quantity_concept<Q1>
+                 && Q1::always_constexpr_unit)
+        constexpr auto
+        with_units(const Q1 & x) {
+            return x.template rescale_ext<Unit>();
+        }
+
         template <typename Q1, typename Q2, auto Unit = Q2::s_unit>
         requires (quantity_concept<Q1>
                   && quantity_concept<Q2>