diff --git a/headers/vmath.hpp/vmath_fun.hpp b/headers/vmath.hpp/vmath_fun.hpp
index d317b20..aca7938 100644
--- a/headers/vmath.hpp/vmath_fun.hpp
+++ b/headers/vmath.hpp/vmath_fun.hpp
@@ -131,19 +131,29 @@ namespace vmath_hpp
 
 namespace vmath_hpp
 {
+    template < typename T >
+    constexpr T dot(T x, T y) noexcept {
+        return x * y;
+    }
+
     template < typename T >
     T length(T x) noexcept {
         return abs(x);
     }
 
     template < typename T >
-    T distance(T x, T y) noexcept {
-        return length(x - y);
+    constexpr T length2(T x) noexcept {
+        return dot(x, x);
     }
 
     template < typename T >
-    T dot(T x, T y) noexcept {
-        return x * y;
+    T distance(T x, T y) noexcept {
+        return length(y - x);
+    }
+
+    template < typename T >
+    constexpr T distance2(T x, T y) noexcept {
+        return length2(y - x);
     }
 
     template < typename T >
@@ -152,12 +162,12 @@ namespace vmath_hpp
     }
 
     template < typename T >
-    T faceforward(T n, T i, T nref) noexcept {
+    constexpr T faceforward(T n, T i, T nref) noexcept {
         return dot(nref, i) < T(0) ? n : -n;
     }
 
     template < typename T >
-    T reflect(T i, T n) noexcept {
+    constexpr T reflect(T i, T n) noexcept {
         return i - n * dot(n, i) * T(2);
     }
 
diff --git a/headers/vmath.hpp/vmath_vec_fun.hpp b/headers/vmath.hpp/vmath_vec_fun.hpp
index 7429762..9e914a1 100644
--- a/headers/vmath.hpp/vmath_vec_fun.hpp
+++ b/headers/vmath.hpp/vmath_vec_fun.hpp
@@ -536,19 +536,31 @@ namespace vmath_hpp
 
 namespace vmath_hpp
 {
+    template < typename T, std::size_t Size >
+    constexpr T dot(const vec<T, Size>& xs, const vec<T, Size>& ys) {
+        return fold([](T acc, T x, T y){
+            return acc + (x * y);
+        }, T(0), xs, ys);
+    }
+
     template < typename T, std::size_t Size >
     T length(const vec<T, Size>& xs) {
         return sqrt(dot(xs, xs));
     }
 
     template < typename T, std::size_t Size >
-    T distance(const vec<T, Size>& xs, const vec<T, Size>& ys) {
-        return length(xs - ys);
+    constexpr T length2(const vec<T, Size>& xs) {
+        return dot(xs, xs);
     }
 
     template < typename T, std::size_t Size >
-    constexpr T dot(const vec<T, Size>& xs, const vec<T, Size>& ys) {
-        return fold(std::plus<>(), T(0), zip(std::multiplies<>(), xs, ys));
+    T distance(const vec<T, Size>& xs, const vec<T, Size>& ys) {
+        return length(ys - xs);
+    }
+
+    template < typename T, std::size_t Size >
+    constexpr T distance2(const vec<T, Size>& xs, const vec<T, Size>& ys) {
+        return length2(ys - xs);
     }
 
     template < typename T >
@@ -565,12 +577,12 @@ namespace vmath_hpp
     }
 
     template < typename T, std::size_t Size >
-    vec<T, Size> faceforward(const vec<T, Size>& n, const vec<T, Size>& i, const vec<T, Size>& nref) {
+    constexpr vec<T, Size> faceforward(const vec<T, Size>& n, const vec<T, Size>& i, const vec<T, Size>& nref) {
         return dot(nref, i) < T(0) ? n : -n;
     }
 
     template < typename T, std::size_t Size >
-    vec<T, Size> reflect(const vec<T, Size>& i, const vec<T, Size>& n) {
+    constexpr vec<T, Size> reflect(const vec<T, Size>& i, const vec<T, Size>& n) {
         return i - n * dot(n, i) * T(2);
     }
 
diff --git a/untests/vmath_fun_tests.cpp b/untests/vmath_fun_tests.cpp
index 419a4f3..72ed18c 100644
--- a/untests/vmath_fun_tests.cpp
+++ b/untests/vmath_fun_tests.cpp
@@ -114,14 +114,20 @@ TEST_CASE("vmath/fun") {
         REQUIRE(length(10.f) == approx(10.f));
         REQUIRE(length(-10.f) == approx(10.f));
 
+        STATIC_REQUIRE(length2(10.f) == approx(100.f));
+        STATIC_REQUIRE(length2(-10.f) == approx(100.f));
+
         REQUIRE(distance(5.f, 10.f) == approx(5.f));
         REQUIRE(distance(-5.f, -10.f) == approx(5.f));
 
+        STATIC_REQUIRE(distance2(5.f, 10.f) == approx(25.f));
+        STATIC_REQUIRE(distance2(-5.f, -10.f) == approx(25.f));
+
         REQUIRE(dot(2.f, 5.f) == approx(10.f));
         REQUIRE(normalize(0.5f) == approx(1.f));
 
-        REQUIRE(faceforward(1.f, 2.f, 3.f) == approx(-1.f));
-        REQUIRE(reflect(1.f, 2.f) == approx(-7.f));
+        STATIC_REQUIRE(faceforward(1.f, 2.f, 3.f) == approx(-1.f));
+        STATIC_REQUIRE(reflect(1.f, 2.f) == approx(-7.f));
         REQUIRE(refract(1.f, 2.f, 1.f) == approx(-7.f));
     }
 }
diff --git a/untests/vmath_vec_fun_tests.cpp b/untests/vmath_vec_fun_tests.cpp
index 6cd0631..11f4221 100644
--- a/untests/vmath_vec_fun_tests.cpp
+++ b/untests/vmath_vec_fun_tests.cpp
@@ -158,15 +158,21 @@ TEST_CASE("vmath/vec_fun") {
         REQUIRE(length(vec2f(10.f,0.f)) == Approx(10.f));
         REQUIRE(length(vec2f(-10.f,0.f)) == Approx(10.f));
 
+        STATIC_REQUIRE(length2(vec2f(10.f,0.f)) == approx(100.f));
+        STATIC_REQUIRE(length2(vec2f(-10.f,0.f)) == approx(100.f));
+
         REQUIRE(distance(vec2f(5.f,0.f), vec2f(10.f,0.f)) == Approx(5.f));
         REQUIRE(distance(vec2f(-5.f,0.f), vec2f(-10.f,0.f)) == Approx(5.f));
 
+        STATIC_REQUIRE(distance2(vec2f(5.f,0.f), vec2f(10.f,0.f)) == approx(25.f));
+        STATIC_REQUIRE(distance2(vec2f(-5.f,0.f), vec2f(-10.f,0.f)) == approx(25.f));
+
         STATIC_REQUIRE(dot(vec2i(1,2),vec2i(3,4)) == 11);
         STATIC_REQUIRE(cross(vec3i(1,0,0),vec3i(0,1,0)) == vec3i(0,0,1));
         REQUIRE(normalize(vec2f(0.5f,0.f)).x == Approx(1.f));
 
-        REQUIRE(faceforward(vec2f(1.f), vec2f(2.f), vec2f(3.f)).x == Approx(-1.f));
-        REQUIRE(reflect(vec2f(1.f), vec2f(2.f)).x == Approx(-15.f));
+        STATIC_REQUIRE(faceforward(vec2f(1.f), vec2f(2.f), vec2f(3.f)).x == approx(-1.f));
+        STATIC_REQUIRE(reflect(vec2f(1.f), vec2f(2.f)).x == approx(-15.f));
         REQUIRE(refract(vec2f(1.f), vec2f(2.f), 1.f).x == Approx(-15.f));
     }