diff --git a/src/checker/dune b/src/checker/dune
index 895db754..fab0d26a 100644
--- a/src/checker/dune
+++ b/src/checker/dune
@@ -3,6 +3,6 @@
   (name main)
   (public_name sidekick-checker)
   (package sidekick-bin)
-  (libraries containers sidekick-bin.lib mtime mtime.clock.os
+  (libraries containers sidekick-bin.lib
              sidekick.util sidekick.tef sidekick.drup)
   (flags :standard -warn-error -a+8 -open Sidekick_util))
diff --git a/src/checker/main.ml b/src/checker/main.ml
index 81822d05..708ef744 100644
--- a/src/checker/main.ml
+++ b/src/checker/main.ml
@@ -83,6 +83,8 @@ let () =
   Printexc.record_backtrace true;
   Sidekick_tef.setup();
 
+  let t1 = Unix.gettimeofday() in
+
   Arg.parse opts (fun f -> files := f :: !files) "checker [opt]* [file]+";
 
   let ok =
@@ -96,7 +98,7 @@ let () =
     | _ -> Error.errorf "expected <problem>? <proof>"
   in
 
-  let t2 = Mtime_clock.elapsed () |> Mtime.Span.to_s in
+  let t2 = Unix.gettimeofday() -. t1 in
   Format.printf "c %s@." (if ok then "OK" else "FAIL");
   Format.printf "c elapsed time: %.3fs@." t2;
   if not ok then exit 1