diff --git a/poly2tri/sweep/sweep_context.cc b/poly2tri/sweep/sweep_context.cc
index 1ec9aed..150f1a0 100644
--- a/poly2tri/sweep/sweep_context.cc
+++ b/poly2tri/sweep/sweep_context.cc
@@ -34,7 +34,13 @@
 
 namespace p2t {
 
-SweepContext::SweepContext(std::vector<Point*> polyline) : points_(polyline)
+SweepContext::SweepContext(std::vector<Point*> polyline) : points_(polyline),
+  front_(0),
+  head_(0),
+  tail_(0),
+  af_head_(0),
+  af_middle_(0),
+  af_tail_(0)
 {
   InitEdges(points_);
 }