diff --git a/kdtree.h b/kdtree.h
index 32bf324..6b8ab66 100644
--- a/kdtree.h
+++ b/kdtree.h
@@ -98,7 +98,7 @@ class KDTree {
 
         // TODO: This copies. Can we split the vector into two without copying?
         std::vector<Point *> left_of_median(points.begin(), points.begin() + middle);
-        std::vector<Point *> right_of_median(points.begin() + middle, points.end());
+        std::vector<Point *> right_of_median(points.begin() + middle + 1, points.end());
 
         // Create node, recursively call to construct subtree
         return new Node(axis, median, build(left_of_median, depth + 1),