diff --git a/compiler/obc/c/async_avr.ml b/compiler/obc/c/async_avr.ml
index 310d33f..96b43fa 100644
--- a/compiler/obc/c/async_avr.ml
+++ b/compiler/obc/c/async_avr.ml
@@ -43,16 +43,14 @@ struct
     | 0 -> abs a
     | b -> gcd b (a mod b)
 
-  let fold_gcd l = List.fold_left gcd (List.hd l) (List.tl l)
-
   let lcm a b = match a, b with
     | 0, _ | _, 0 -> 0
     | _ -> abs (a * b) / (gcd a b)
 
   let fold_lcm l = List.fold_left lcm (List.hd l) (List.tl l)
 
-  let count_of_ack base = function
-    | Timer_ms ms -> ms / base
+  let ms_of_ack = function
+    | Timer_ms ms -> ms
 
   let incr_mod name modulo =
     let one_const = Cconst (Ccint 1) in
@@ -60,12 +58,12 @@ struct
     let incr = Cbop ("+", Cvar name, one_const) in
     Caffect (CLvar name, Cbop ("%", incr, modulo_const))
 
-  let call_step_async base tick_var (od, ack) =
+  let call_step_async tick_var (od, ack) =
     let step = (cname_of_qn od.o_class) ^ "_async_step" in
     let global = async_global_var_name od in
     let call = Csexpr (Cfun_call (step, [Caddrof (Cvar global)])) in
     let zero = Cconst (Ccint 0) in
-    let timer = Cconst (Ccint (count_of_ack base ack)) in
+    let timer = Cconst (Ccint (ms_of_ack ack)) in
     let cond = Cbop ("==", Cbop ("%", tick_var, timer), zero) in
     Cif (cond, [call], [])
 
@@ -83,12 +81,11 @@ struct
     let body = match timers with
       | [] -> []
       | _ ->
-         let base_timer = fold_gcd timers in
-         let max_timer = fold_lcm timers in
+         let lcm_timer = fold_lcm timers in
          let steps =
-           List.map (call_step_async base_timer (Cvar "tick")) trans
+           List.map (call_step_async (Cvar "tick")) trans
          in
-         let incr = incr_mod "tick" (max_timer / base_timer) in
+         let incr = incr_mod "tick" lcm_timer in
          steps @ [incr]
     in
     (* run_timers is declared in avr.h (because of the ISR macro which