diff --git a/include/boost/geometry/algorithms/detail/is_valid/complement_graph.hpp b/include/boost/geometry/algorithms/detail/is_valid/complement_graph.hpp
index 38b2cda1e..0a4d67e30 100644
--- a/include/boost/geometry/algorithms/detail/is_valid/complement_graph.hpp
+++ b/include/boost/geometry/algorithms/detail/is_valid/complement_graph.hpp
@@ -198,7 +198,7 @@ public:
 
     // inserts a ring vertex in the graph and returns its handle
     // ring id's are zero-based (so the first interior ring has id 1)
-    vertex_handle add_vertex(std::size_t id)
+    vertex_handle add_vertex(int id)
     {
         return m_vertices.insert(vertex(id)).first;
     }
@@ -212,7 +212,7 @@ public:
         if ( res.second )
         {
             // a new element is inserted
-            res.first->id( m_num_rings + m_num_turns );
+            res.first->id( static_cast<int>(m_num_rings + m_num_turns) );
             ++m_num_turns;
         }
         return res.first;
diff --git a/include/boost/geometry/algorithms/detail/is_valid/polygon.hpp b/include/boost/geometry/algorithms/detail/is_valid/polygon.hpp
index b9f3e9ca0..cdd1b2dc1 100644
--- a/include/boost/geometry/algorithms/detail/is_valid/polygon.hpp
+++ b/include/boost/geometry/algorithms/detail/is_valid/polygon.hpp
@@ -155,11 +155,6 @@ protected:
 
 
 
-    static inline std::size_t get_vertex_id(int ring_id)
-    {
-        return static_cast<std::size_t>(ring_id + 1);
-    }
-
     template <typename TurnIterator>
     static inline bool has_connected_interior(Polygon const& polygon,
                                               TurnIterator first,
@@ -175,9 +170,9 @@ protected:
         for (TurnIterator tit = first; tit != beyond; ++tit)
         {
             typename graph::vertex_handle v1 = g.add_vertex
-                ( get_vertex_id(tit->operations[0].seg_id.ring_index) );
+                ( tit->operations[0].seg_id.ring_index + 1 );
             typename graph::vertex_handle v2 = g.add_vertex
-                ( get_vertex_id(tit->operations[0].other_id.ring_index) );
+                ( tit->operations[0].other_id.ring_index + 1 );
             typename graph::vertex_handle vip = g.add_vertex(tit->point);
 
             g.add_edge(v1, vip);