diff --git a/src/RayTracer.cc b/src/RayTracer.cc
index a257fa1..1da82d8 100644
--- a/src/RayTracer.cc
+++ b/src/RayTracer.cc
@@ -32,8 +32,8 @@ void RayTracer::render(Scene *scene) {
   Vector3f up = scene->getUpVector();
   float vpHeight = 2 * tan(fov / 180 * 3.14159265 / 2) * lookAt.norm();
   float vpWidth = vpHeight * width / height;
-  Vector3f vpU = Vector3f(vpWidth, 0, 0);
-  Vector3f vpV = Vector3f(0, -vpHeight, 0);
+  Vector3f vpU = Vector3f(-vpWidth, 0, 0);
+  Vector3f vpV = Vector3f(0, vpHeight, 0);
   Vector3f du = vpU / width;
   Vector3f dv = vpV / height;