diff --git a/src/GLObjects/Mesh.cpp b/src/GLObjects/Mesh.cpp
index d0cbb0f..efdccf1 100644
--- a/src/GLObjects/Mesh.cpp
+++ b/src/GLObjects/Mesh.cpp
@@ -3,7 +3,11 @@
 #include <glm/vec3.hpp>
 #include <iostream>
 
-Mesh::Mesh(ShaderProgram* shader, std::size_t size) : GLObject(shader), _size(size), _xs(size), _ys(size), _normals(2*size*size) {
+Mesh::Mesh(ShaderProgram* shader, std::size_t size) : GLObject(shader),
+                                                      _size(size),
+                                                      _xs(size),
+                                                      _ys(size),
+                                                      _normals(2*size*size) {
 	_vertexCount = _size*_size;
 	_indexCount = (_size - 1)*(_size - 1)*6;
 	_vertices = std::make_unique<Vertex[]>(_vertexCount);
@@ -28,7 +32,7 @@ void Mesh::generateVertices() const {
     }
 }
 
-inline size_t Mesh::normalIndex(size_t x, size_t y) {
+inline size_t Mesh::normalIndex(size_t x, size_t y) const {
     return  2*(x + y*_size);
 }
 
@@ -56,8 +60,8 @@ void Mesh::updateVertices() const {
             glm::vec3 v2 = p2 - p3;
             glm::vec3 v3 = p4 - p3;
 
-            glm::vec3 norm1 = glm::cross(v2, v1);
-            glm::vec3 norm2 = glm::cross(v3, v2);
+            glm::vec3 norm1 = glm::cross(v1, v2);
+            glm::vec3 norm2 = glm::cross(v2, v3);
 
             _normals.emplace_back(norm1);
             _normals.emplace_back(norm2);
@@ -68,8 +72,26 @@ void Mesh::updateVertices() const {
     //    Normal of vertex is an average of normals of adjacent triangles
     for(std::size_t j = 0; j < _size; ++j) {
         for (std::size_t i = 0; i < _size; ++i) {
+            glm::vec3 normal;
+
             size_t idx1 = normalIndex(i - 1, j - 1);
+            for(size_t k = idx1; k < idx1 + 3; ++k) {
+                if(k >= 0) {
+                    normal += _normals[k];
+                }
+            }
+
             size_t idx2 = normalIndex(i - 1, j);
+            for(size_t k = idx2; k < idx2 + 3; ++k) {
+                if(k >= 0) {
+                    normal += _normals[k];
+                }
+            }
+
+            size_t idx = j*(_size - 1) + i;
+            _vertices[idx].nx = normal.x;
+            _vertices[idx].ny = normal.y;
+            _vertices[idx].nz = normal.z;
         }
     }
 }
diff --git a/src/GLObjects/Mesh.h b/src/GLObjects/Mesh.h
index 7f2c2a0..beaeafb 100644
--- a/src/GLObjects/Mesh.h
+++ b/src/GLObjects/Mesh.h
@@ -25,7 +25,7 @@ public:
 	virtual ~Mesh();
 
 private:
-    size_t normalIndex(size_t x, size_t y);
+    size_t normalIndex(size_t x, size_t y) const;
 
 protected:
 	void generateVertices() const override final;