diff --git a/Polygon/include/CGAL/Polygon_2/Polygon_2_impl.h b/Polygon/include/CGAL/Polygon_2/Polygon_2_impl.h
index 2870d536ada..47f58ea9305 100644
--- a/Polygon/include/CGAL/Polygon_2/Polygon_2_impl.h
+++ b/Polygon/include/CGAL/Polygon_2/Polygon_2_impl.h
@@ -90,7 +90,7 @@ template <class Traits_P, class Container_P>
 std::istream &
 operator>>(std::istream &is, Polygon_2<Traits_P,Container_P>& p)
 {
-  int n; // number of vertices
+  int n = 0; // number of vertices
   is >> n;
   typename Traits_P::Point_2 point;