src/Pure/Concurrent/future.ML

             let
               val {ready, pending, running} = Task_Queue.status (! queue);
               val total = length (! workers);
               val active = count_active ();
             in
-              "SCHEDULE " ^ string_of_int (Time.toMilliseconds now) ^ ": " ^
+              "SCHEDULE " ^ Time.toString now ^ ": " ^
                 string_of_int ready ^ " ready, " ^
                 string_of_int pending ^ " pending, " ^
                 string_of_int running ^ " running; " ^
                 string_of_int total ^ " workers, " ^
                 string_of_int active ^ " active"