diff --git a/poly2d/f2d_tri_holes.cpp b/poly2d/f2d_tri_holes.cpp
index 37844ac..e8406bd 100644
--- a/poly2d/f2d_tri_holes.cpp
+++ b/poly2d/f2d_tri_holes.cpp
@@ -169,11 +169,15 @@ void insert_polygon(CDT &cdt, const Polygon_2 &polygon)
 
 static const struct v2d *find_point(const struct p2d *p, double x, double y)
 {
-	const struct v2d *v;
+	const struct v2d *v = p->v;
 
-	for (v = p->v; v; v = v->next)
+	while (v) {
 		if (v->x == x && v->y == y)
 			break;
+		v = v->next;
+		if (v == p->v)
+			return NULL;
+	}
 	return v;
 }