diff --git a/src/tracedAtomic.ml b/src/tracedAtomic.ml
index b8d0712..b75f749 100644
--- a/src/tracedAtomic.ml
+++ b/src/tracedAtomic.ml
@@ -290,8 +290,7 @@ let _set_to_str s =
   IntSet.to_seq s |> List.of_seq |> List.map Int.to_string |> String.concat ", "
 
 let rec explore_source depth func state sleep_sets =
-  let _sleep = last_element sleep_sets in
-  let sleep = ref IntSet.empty in
+  let sleep = last_element sleep_sets in
   let s = last_element state in
   (* Printf.printf "[depth=%d] explore (backtrack=[%s], sleep=[%s], enabled=[%s])\n%!" depth
      (set_to_str s.backtrack) (set_to_str !sleep) (set_to_str s.enabled); *)
@@ -443,17 +442,17 @@ let rec explore_source depth func state sleep_sets =
               (List.length prefix - 1)
               prefix_top.run_proc
               (atomic_op_str prefix_top.run_op); *)
-            let _prefix_top_sleep =
+            let prefix_top_sleep =
               !(List.nth sleep_sets (List.length prefix - 1))
             in
             if
               IntSet.(
                 cardinal
-                  (inter prefix_top.backtrack ( initials )))
+                  (inter prefix_top.backtrack (diff initials prefix_top_sleep)))
               = 0
             then (
               let _initial =
-                match IntSet.(min_elt_opt ( initials )) with
+                match IntSet.(min_elt_opt (diff initials prefix_top_sleep)) with
                 | Some initial -> initial
                 | None -> IntSet.min_elt initials
               in