diff --git a/autobrake_test.p8 b/autobrake_test.p8
index b0b55ca..fa90df6 100644
--- a/autobrake_test.p8
+++ b/autobrake_test.p8
@@ -165,10 +165,23 @@ constraints = {
 
 function constraints:constrain(s, want)
  self.color=10
+ if (not self.xmin) return want
 
- local v1 = calc_velocity(s.dx, want, s.maxspd, s.drag)
- local bd, bf = brake_dist(v1, s.thrust + s.drag)
-
+ -- bmx: brake max
+ local v1, bmx = calc_velocity(s.dx, want, s.maxspd, s.drag), s.thrust + s.drag
+ local bd, bf = brake_dist(v1, bmx)
+ local bx, txm = s.x + bd, self.xmax
+ if bx < self.xmin then
+  self.color = 9
+  want = s.thrust
+  txm = self.xmin
+  v1 = calc_velocity(s.dx, want, s.maxspd, s.drag)
+  bd, bf = brake_dist(v1, bmx)
+  bx  = bd + s.x
+ end
+ if (bx < txm) return want
+ self.color = 8
+ -- TODO: implement overshot constraint
  return want
 end