diff --git a/y2016/vision/target_receiver.cc b/y2016/vision/target_receiver.cc
index 3f3c321..b861335 100644
--- a/y2016/vision/target_receiver.cc
+++ b/y2016/vision/target_receiver.cc
@@ -26,7 +26,7 @@
 double TargetWidth(double lx, double ly, double rx, double ry) {
   double dx = lx - rx;
   double dy = ly - ry;
-  return ::std::sqrt(dx * dx + dy * dy);
+  return ::std::hypot(dx, dy);
 }
 
 void SelectTargets(const VisionData &left_target,