diff --git a/tests/codex/utils/testtimer.nim b/tests/codex/utils/testtimer.nim
index cf05df19..79b95e42 100644
--- a/tests/codex/utils/testtimer.nim
+++ b/tests/codex/utils/testtimer.nim
@@ -21,11 +21,11 @@ asyncchecksuite "Timer":
   var numbersState = 0
   var lettersState = 'a'
 
-  proc numbersCallback(): Future[void] {.async: (raises: []).} =
+  proc numbersCallback(): Future[void] {.async: (raises: [CancelledError]).} =
     output &= $numbersState
     inc numbersState
 
-  proc lettersCallback(): Future[void] {.async: (raises: []).} =
+  proc lettersCallback(): Future[void] {.async: (raises: [CancelledError]).} =
     output &= $lettersState
     inc lettersState