diff --git a/zigrtiow/src/main.zig b/zigrtiow/src/main.zig
index 3c794d4..9494faf 100644
--- a/zigrtiow/src/main.zig
+++ b/zigrtiow/src/main.zig
@@ -15,8 +15,7 @@ const Point3 = vec.Point3;
 const Ray = ray.Ray;
 const Sphere = sphere.Sphere;
 const Vec3 = vec.Vec3;
-const random_unit_vector = vec.random_unit_vector;
-const random_in_unit_sphere = vec.random_in_unit_sphere;
+const random_in_hemisphere = vec.random_in_hemisphere;
 const info = std.log.info;
 const write_color = color.write_color;
 
@@ -26,7 +25,7 @@ fn ray_color(r: Ray, world: Hittable, depth: isize) Color {
 
     var hit = world.hit(r, 0.0001, std.math.inf(f32));
     if (hit) |rec| {
-        const target = rec.p.add(rec.normal.add(random_unit_vector()));
+        const target = rec.p.add(rec.normal.add(random_in_hemisphere(rec.normal)));
         return ray_color(Ray.init(rec.p, target.sub(rec.p)), world, depth - 1).scale(0.5);
     }
     var unit_direction = r.direction().unit();
diff --git a/zigrtiow/src/vec.zig b/zigrtiow/src/vec.zig
index df190da..298547d 100644
--- a/zigrtiow/src/vec.zig
+++ b/zigrtiow/src/vec.zig
@@ -64,6 +64,14 @@ pub fn random_in_unit_sphere() Vec3 {
 pub fn random_unit_vector() Vec3 {
     return random_in_unit_sphere().unit();
 }
+pub fn random_in_hemisphere(normal: Vec3) Vec3 {
+    const in_unit_sphere = random_in_unit_sphere();
+    if (in_unit_sphere.dot(normal) > 0.0) { // In the same hemisphere as the normal
+        return in_unit_sphere;
+    } else {
+        return in_unit_sphere.scale(-1);
+    }
+}
 
 pub const Color = Vec3;
 pub const Point3 = Vec3;