diff --git a/codex/contracts/clock.nim b/codex/contracts/clock.nim
index b7863539..860f2188 100644
--- a/codex/contracts/clock.nim
+++ b/codex/contracts/clock.nim
@@ -68,11 +68,13 @@ method stop*(clock: OnChainClock) {.async.} =
   await clock.trackedFutures.cancelTracked()
   clock.started = false
 
-method now*(clock: OnChainClock): SecondsSince1970 =
+method now*(clock: OnChainClock): SecondsSince1970 {.raises: [].} =
   doAssert clock.started, "clock should be started before calling now()"
   return toUnix(getTime() + clock.offset)
 
-method waitUntil*(clock: OnChainClock, time: SecondsSince1970) {.async.} =
+method waitUntil*(
+    clock: OnChainClock, time: SecondsSince1970
+) {.async: (raises: [CancelledError]).} =
   while (let difference = time - clock.now(); difference > 0):
     clock.newBlock.clear()
     discard await clock.newBlock.wait().withTimeout(chronos.seconds(difference))
diff --git a/codex/validation.nim b/codex/validation.nim
index 58a0e6b7..d9f8fb5e 100644
--- a/codex/validation.nim
+++ b/codex/validation.nim
@@ -80,7 +80,7 @@ proc removeSlotsThatHaveEnded(validation: Validation) {.async.} =
 
 proc markProofAsMissing(
     validation: Validation, slotId: SlotId, period: Period
-) {.async.} =
+) {.async: (raises: [CancelledError]).} =
   logScope:
     currentPeriod = validation.getCurrentPeriod()
 
@@ -91,18 +91,18 @@ proc markProofAsMissing(
     else:
       let inDowntime {.used.} = await validation.market.inDowntime(slotId)
       trace "Proof not missing", checkedPeriod = period, inDowntime
-  except CancelledError:
-    raise
+  except CancelledError as e:
+    raise e
   except CatchableError as e:
     error "Marking proof as missing failed", msg = e.msg
 
-proc markProofsAsMissing(validation: Validation) {.async.} =
+proc markProofsAsMissing(validation: Validation) {.async: (raises: [CancelledError]).} =
   let slots = validation.slots
   for slotId in slots:
     let previousPeriod = validation.getCurrentPeriod() - 1
     await validation.markProofAsMissing(slotId, previousPeriod)
 
-proc run(validation: Validation) {.async: (raises: []).} =
+proc run(validation: Validation) {.async: (raises: [CancelledError]).} =
   trace "Validation started"
   try:
     while true: