diff --git a/src/SFML/Graphics/Shape.cpp b/src/SFML/Graphics/Shape.cpp
index a7726827..a46dca94 100644
--- a/src/SFML/Graphics/Shape.cpp
+++ b/src/SFML/Graphics/Shape.cpp
@@ -36,18 +36,12 @@ namespace
     // Compute the normal of a segment
     sf::Vector2f computeNormal(const sf::Vector2f& p1, const sf::Vector2f& p2)
     {
-        sf::Vector2f normal(p1.y - p2.y, p2.x - p1.x);
-        float length = std::sqrt(normal.x * normal.x + normal.y * normal.y);
+        sf::Vector2f normal = (p2 - p1).perpendicular();
+        float length = normal.length();
         if (length != 0.f)
             normal /= length;
         return normal;
     }
-
-    // Compute the dot product of two vectors
-    float dotProduct(const sf::Vector2f& p1, const sf::Vector2f& p2)
-    {
-        return p1.x * p2.x + p1.y * p2.y;
-    }
 }
 
 
@@ -280,9 +274,9 @@ void Shape::updateOutline()
 
         // Make sure that the normals point towards the outside of the shape
         // (this depends on the order in which the points were defined)
-        if (dotProduct(n1, m_vertices[0].position - p1) > 0)
+        if (n1.dot(m_vertices[0].position - p1) > 0)
             n1 = -n1;
-        if (dotProduct(n2, m_vertices[0].position - p1) > 0)
+        if (n2.dot(m_vertices[0].position - p1) > 0)
             n2 = -n2;
 
         // Combine them to get the extrusion direction