diff --git a/bench/algorithm/binarytrees/1.ml b/bench/algorithm/binarytrees/1.ml
index c11c4280..604416a3 100644
--- a/bench/algorithm/binarytrees/1.ml
+++ b/bench/algorithm/binarytrees/1.ml
@@ -1,20 +1,19 @@
-class node left' right' =
-  object
-    val left : node option = left'
+module Node = struct
+  type t = { left : t option; right : t option }
 
-    val right : node option = right'
+  let create left right = { left; right }
 
-    method check =
-      1
-      + (match left with None -> 0 | Some l -> l#check)
-      + match right with None -> 0 | Some r -> r#check
-  end
+  let rec check node =
+    1
+    + (match node.left with None -> 0 | Some l -> check l)
+    + match node.right with None -> 0 | Some r -> check r
+end
 
 let rec make d =
-  if d = 0 then new node None None
+  if d = 0 then Node.create None None
   else
     let d = d - 1 in
-    new node (Some (make d)) (Some (make d))
+    Node.create (Some (make d)) (Some (make d))
 
 let min_depth = 4
 
@@ -25,7 +24,7 @@ let max_depth =
 let stretch_depth = max_depth + 1
 
 let () =
-  let c = (make stretch_depth)#check in
+  let c = Node.check @@ make stretch_depth in
   Printf.printf "stretch tree of depth %i\t check: %i\n" stretch_depth c
 
 let long_lived_tree = make max_depth
@@ -36,13 +35,12 @@ let loop_depths d =
     let niter = 1 lsl (max_depth - d + min_depth) in
     let c = ref 0 in
     for _ = 1 to niter do
-      c := !c + (make d)#check
+      c := !c + Node.check (make d)
     done;
     Printf.printf "%i\t trees of depth %i\t check: %i\n" niter d !c
   done
 
 let () =
-  flush stdout;
   loop_depths min_depth;
   Printf.printf "long lived tree of depth %i\t check: %i\n" max_depth
-    long_lived_tree#check
+    (Node.check long_lived_tree)