diff --git a/codex/clock.nim b/codex/clock.nim
index c02e04aa..5c63d15e 100644
--- a/codex/clock.nim
+++ b/codex/clock.nim
@@ -1,3 +1,5 @@
+{.push raises: [].}
+
 import pkg/chronos
 import pkg/stew/endians2
 import pkg/upraises
@@ -11,7 +13,9 @@ type
 method now*(clock: Clock): SecondsSince1970 {.base, gcsafe, upraises: [].} =
   raiseAssert "not implemented"
 
-method waitUntil*(clock: Clock, time: SecondsSince1970) {.base, async.} =
+method waitUntil*(
+    clock: Clock, time: SecondsSince1970
+) {.base, async: (raises: [CancelledError]).} =
   raiseAssert "not implemented"
 
 method start*(clock: Clock) {.base, async.} =