diff --git a/rtiww/src/main.cpp b/rtiww/src/main.cpp
index 10a54f0..60e281d 100644
--- a/rtiww/src/main.cpp
+++ b/rtiww/src/main.cpp
@@ -46,9 +46,9 @@ int main() {
   hittable_list world;
 
   auto material_ground = make_shared<lambertian>(color(0.8, 0.8, 0.0));
-  auto material_center = make_shared<dielectric>(1.5);
+  auto material_center = make_shared<lambertian>(color(0.1, 0.2, 0.5));
   auto material_left = make_shared<dielectric>(1.5);
-  auto material_right = make_shared<metal>(color(0.8, 0.6, 0.2), 1.0);
+  auto material_right = make_shared<metal>(color(0.8, 0.6, 0.2), 0.0);
 
   world.add(
       make_shared<sphere>(point3(0.0, -100.5, -1.0), 100.0, material_ground));
diff --git a/rtiww/src/material.h b/rtiww/src/material.h
index c3837e5..e026201 100644
--- a/rtiww/src/material.h
+++ b/rtiww/src/material.h
@@ -57,14 +57,23 @@ public:
 
   virtual bool scatter(const ray &r_in, const hit_record &rec,
                        color &attenuation, ray &scattered) const override {
-    attenuation = color(1.0, 1.0, 1.0);
-    double refraction_ratio = rec.front_face ? (1.0 / ir) : ir;
+      attenuation = color(1.0, 1.0, 1.0);
+      double refraction_ratio = rec.front_face ? (1.0/ir) : ir;
 
-    vec3 unit_direction = unit_vector(r_in.direction());
-    vec3 refracted = refract(unit_direction, rec.normal, refraction_ratio);
+      vec3 unit_direction = unit_vector(r_in.direction());
+      double cos_theta = fmin(dot(-unit_direction, rec.normal), 1.0);
+      double sin_theta = sqrt(1.0 - cos_theta*cos_theta);
 
-    scattered = ray(rec.p, refracted);
-    return true;
+      bool cannot_refract = refraction_ratio * sin_theta > 1.0;
+      vec3 direction;
+
+      if (cannot_refract)
+          direction = reflect(unit_direction, rec.normal);
+      else
+          direction = refract(unit_direction, rec.normal, refraction_ratio);
+
+      scattered = ray(rec.p, direction);
+      return true;
   }
 
 public: