diff --git a/contrib/poly2tri/poly2tri/sweep/sweep_context.cc b/contrib/poly2tri/poly2tri/sweep/sweep_context.cc
index 672303c53..c9dd5a8c4 100644
--- a/contrib/poly2tri/poly2tri/sweep/sweep_context.cc
+++ b/contrib/poly2tri/poly2tri/sweep/sweep_context.cc
@@ -96,11 +96,11 @@ void SweepContext::InitTriangulation()
 
 void SweepContext::InitEdges(std::vector<Point*> polyline)
 {
-  std::size_t num_points = polyline.size();
-  for (std::size_t i = 0; i < num_points - 1; i++) {
-    edge_list.push_back(new Edge(*polyline[i], *polyline[i + 1]));
+  int num_points = polyline.size();
+  for (int i = 0; i < num_points; i++) {
+    int j = i < num_points - 1 ? i + 1 : 0;
+    edge_list.push_back(new Edge(*polyline[i], *polyline[j]));
   }
-  edge_list.push_back(new Edge(*polyline.back(), *polyline.front()));
 }
 
 Point* SweepContext::GetPoint(const int& index)
diff --git a/contrib/poly2tri/poly2tri/sweep/sweep_context.h b/contrib/poly2tri/poly2tri/sweep/sweep_context.h
index 4b098e860..266408dc2 100644
--- a/contrib/poly2tri/poly2tri/sweep/sweep_context.h
+++ b/contrib/poly2tri/poly2tri/sweep/sweep_context.h
@@ -64,7 +64,7 @@ void set_tail(Point* p1);
 
 Point* tail();
 
-std::size_t point_count();
+int point_count();
 
 Node& LocateNode(Point& point);
 
@@ -156,7 +156,7 @@ inline AdvancingFront* SweepContext::front()
   return front_;
 }
 
-inline std::size_t SweepContext::point_count()
+inline int SweepContext::point_count()
 {
   return points_.size();
 }