diff --git a/tests/bin/emit1.ml b/tests/bin/emit1.ml
index c7adf5f6..1db309fc 100644
--- a/tests/bin/emit1.ml
+++ b/tests/bin/emit1.ml
@@ -5,11 +5,15 @@ let (let@) f x = f x
 
 let sleep_inner = ref 0.1
 let sleep_outer = ref 2.0
+let num_sleep = ref 0
 
 let run () =
   Printf.printf "collector is on %S\n%!" (Opentelemetry_client_ocurl.get_url());
   T.GC_metrics.basic_setup();
 
+  T.Metrics_callbacks.register (fun () ->
+    T.Metrics.[ sum ~name:"num-sleep" ~is_monotonic:true [int !num_sleep] ]);
+
   let i = ref 0 in
   while true do
     let@ scope =
@@ -22,7 +26,9 @@ let run () =
       let@ scope = T.Trace.with_ ~kind:T.Span.Span_kind_internal ~scope
           ~attrs:["j", `Int j]
           "loop.inner" in
+
       Unix.sleepf !sleep_outer;
+      incr num_sleep;
 
       incr i;
 
@@ -33,7 +39,10 @@ let run () =
         (* allocate some stuff *)
         let _arr = Sys.opaque_identity @@ Array.make (25 * 25551) 42.0 in
         ignore _arr;
+
         Unix.sleepf !sleep_inner;
+        incr num_sleep;
+
         if j=4 && !i mod 13 = 0 then failwith "oh no"; (* simulate a failure *)
 
         T.Trace.add_event scope (fun()->T.Event.make "done with alloc");