diff --git a/scripts/ci-hermit-retry.sh b/scripts/ci-hermit-retry.sh
index b3d9795e68..5ac7668d45 100755
--- a/scripts/ci-hermit-retry.sh
+++ b/scripts/ci-hermit-retry.sh
@@ -55,25 +55,33 @@ for attempt in $(seq 1 "$attempts"); do
   set -m
   "$@" &
   pid=$!
+  # The watchdog exits 0 if stopped before it signals the attempt and 124 once
+  # it has, so a timeout is reported only when the watchdog really stopped the
+  # attempt. Elapsed time cannot tell: $SECONDS counts whole wall-clock
+  # seconds, so an instant failure that straddled a second boundary looked
+  # like it had run for the whole 1s deadline.
   (
+    trap 'exit 0' TERM
     sleep "$deadline"
+    trap 'exit 124' TERM
     kill -TERM -- "-$pid" 2>/dev/null || exit 0
     sleep "$kill_after"
     kill -KILL -- "-$pid" 2>/dev/null || true
+    exit 124
   ) >/dev/null 2>&1 &
   watchdog=$!
   set +m
-  started=$SECONDS
   rc=0
   # Bash reports a job killed by a signal on wait's stderr; the warning below
   # says the same thing.
   wait "$pid" 2>/dev/null || rc=$?
   kill -- "-$watchdog" 2>/dev/null || true
-  wait "$watchdog" 2>/dev/null || true
+  watchdog_rc=0
+  wait "$watchdog" 2>/dev/null || watchdog_rc=$?
   [ "$rc" -eq 0 ] && exit 0
   # The leader can exit on TERM while a child that ignores it lives on.
   kill -KILL -- "-$pid" 2>/dev/null || true
-  if [ $((SECONDS - started)) -ge "$deadline" ]; then
+  if [ "$watchdog_rc" -eq 124 ]; then
     echo "::warning::attempt $attempt/$attempts timed out after ${deadline}s: $*"
   else
     echo "::warning::attempt $attempt/$attempts failed (exit $rc): $*"
diff --git a/scripts/ci-hermit-retry.test.mjs b/scripts/ci-hermit-retry.test.mjs
index 14fff2fa4f..7eb131fc1f 100644
--- a/scripts/ci-hermit-retry.test.mjs
+++ b/scripts/ci-hermit-retry.test.mjs
@@ -98,6 +98,18 @@ test("persistent failure backs off between attempts and stops at the budget", ()
   assert.ok(r.seconds >= 3, `took ${r.seconds}s`);
 });
 
+// A quick failure that straddles a wall-clock second boundary is still a
+// failure: only the watchdog stopping the attempt makes it a timeout. Start
+// 0.8s into a second so the 0.4s attempt crosses the next boundary while
+// finishing well inside its 1s deadline.
+test("a quick failure across a second boundary is not a timeout", async () => {
+  await sleep((1800 - (Date.now() % 1000)) % 1000);
+  const r = run("sleep 0.4; exit 7", { CI_HERMIT_ATTEMPTS: "1" });
+  assert.equal(r.status, 1, r.stdout);
+  assert.match(r.stdout, /attempt 1\/1 failed \(exit 7\)/);
+  assert.doesNotMatch(r.stdout, /timed out/);
+});
+
 test("no command is a usage error", () => {
   assert.equal(spawnSync("bash", [script]).status, 2);
 });