diff --git a/src/include/units/quantity.h b/src/include/units/quantity.h
index 72e53405..e72be5f6 100644
--- a/src/include/units/quantity.h
+++ b/src/include/units/quantity.h
@@ -346,6 +346,9 @@ public:
   }
 };
 
+template<ScalableNumber V>
+/* implicit */ quantity(V) -> quantity<dim_one, one, V>;
+
 namespace detail {
 
 template<typename D, typename U, typename Rep>
diff --git a/test/unit_test/static/quantity_test.cpp b/test/unit_test/static/quantity_test.cpp
index 54783bc7..e9503b6d 100644
--- a/test/unit_test/static/quantity_test.cpp
+++ b/test/unit_test/static/quantity_test.cpp
@@ -319,6 +319,9 @@ static_assert(50._q_m / 100._q_m == dimensionless<percent>(50));
 
 static_assert(dimensionless<one>(dimensionless<percent>(50)).count() == 0.5);
 
+static_assert(std::is_same_v<decltype(quantity{1}), dimensionless<one, int>>);
+static_assert(std::is_same_v<decltype(quantity{1.23}), dimensionless<one, double>>);
+
 // time
 
 static_assert(1_q_h == 3600_q_s);