diff --git a/headers/vmath.hpp/vmath_qua_fun.hpp b/headers/vmath.hpp/vmath_qua_fun.hpp
index f4ce40f..684734d 100644
--- a/headers/vmath.hpp/vmath_qua_fun.hpp
+++ b/headers/vmath.hpp/vmath_qua_fun.hpp
@@ -62,6 +62,67 @@ namespace vmath_hpp
         return (xs = (xs - ys));
     }
 
+    // operator*
+
+    template < typename T >
+    [[nodiscard]] constexpr qua<T> operator*(const qua<T>& xs, T y) {
+        return qua(vec{xs} * y);
+    }
+
+    template < typename T >
+    [[nodiscard]] constexpr qua<T> operator*(T x, const qua<T>& ys) {
+        return qua(x * vec{ys});
+    }
+
+    template < typename T >
+    [[nodiscard]] constexpr vec<T, 3> operator*(const vec<T, 3>& xs, const qua<T>& ys) {
+        const vec qv2 = cross(ys.v, xs) * T(2);
+        return xs + qv2 * ys.s + cross(ys.v, qv2);
+    }
+
+    template < typename T >
+    [[nodiscard]] constexpr qua<T> operator*(const qua<T>& xs, const qua<T>& ys) {
+        return {
+            cross(ys.v, xs.v) + ys.s * xs.v + xs.s * ys.v,
+            ys.s * xs.s - dot(ys.v, xs.v)};
+    }
+
+    // operator*=
+
+    template < typename T >
+    constexpr qua<T>& operator*=(qua<T>& xs, T y) {
+        return (xs = (xs * y));
+    }
+
+    template < typename T >
+    constexpr vec<T, 3>& operator*=(vec<T, 3>& xs, const qua<T>& ys) {
+        return (xs = (xs * ys));
+    }
+
+    template < typename T >
+    constexpr qua<T>& operator*=(qua<T>& xs, const qua<T>& ys) {
+        return (xs = (xs * ys));
+    }
+
+    // operator/
+
+    template < typename T >
+    [[nodiscard]] constexpr qua<T> operator/(const qua<T>& xs, T y) {
+        return qua(vec{xs} / y);
+    }
+
+    template < typename T >
+    [[nodiscard]] constexpr qua<T> operator/(T x, const qua<T>& ys) {
+        return qua(x / vec{ys});
+    }
+
+    // operator/=
+
+    template < typename T >
+    constexpr qua<T>& operator/=(qua<T>& xs, T y) {
+        return (xs = (xs / y));
+    }
+
     // operator==
 
     template < typename T >
diff --git a/untests/vmath_qua_fun_tests.cpp b/untests/vmath_qua_fun_tests.cpp
index b3baf6c..fccd77c 100644
--- a/untests/vmath_qua_fun_tests.cpp
+++ b/untests/vmath_qua_fun_tests.cpp
@@ -32,5 +32,35 @@ TEST_CASE("vmath/qua_fun") {
             REQUIRE(&v == &(v -= qua{3,4,5,6}));
             REQUIRE(v == qua{-2,-2,-2,-2});
         }
+
+        STATIC_REQUIRE(qua(1,2,3,4) * 2 == qua(2,4,6,8));
+        STATIC_REQUIRE(qua(2,4,6,8) / 2 == qua(1,2,3,4));
+
+        STATIC_REQUIRE(2 * qua(1,2,3,4) == qua(2,4,6,8));
+        STATIC_REQUIRE(8 / qua(1,2,4,8) == qua(8,4,2,1));
+
+        {
+            qua v{1,2,3,4};
+            REQUIRE(&v == &(v *= 2));
+            REQUIRE(v == qua{2,4,6,8});
+            REQUIRE(&v == &(v *= qua<int>{}));
+            REQUIRE(v == qua{2,4,6,8});
+        }
+
+        {
+            qua v{2,4,6,8};
+            REQUIRE(&v == &(v /= 2));
+            REQUIRE(v == qua{1,2,3,4});
+        }
+
+        {
+            float3 v{1,0,0};
+            REQUIRE(&v == &(v *= fqua{0,0,0.7071067812f,0.7071067812f}));
+            REQUIRE(v == uapprox3(0.f,1.f,0.f));
+        }
+
+        STATIC_REQUIRE(fqua{} * fqua{} == fqua{});
+        STATIC_REQUIRE(float3{1,2,3} * fqua{} == uapprox3(1.f,2.f,3.f));
+        STATIC_REQUIRE(float3{1,0,0} * fqua{0,0,0.7071067812f,0.7071067812f} == uapprox3(0.f,1.f,0.f));
     }
 }