diff --git a/modules/zfs/cmd/zfs-tools/manifest_test.go b/modules/zfs/cmd/zfs-tools/manifest_test.go
index ca82669c4..b917c57a1 100644
--- a/modules/zfs/cmd/zfs-tools/manifest_test.go
+++ b/modules/zfs/cmd/zfs-tools/manifest_test.go
@@ -121,10 +121,16 @@ func TestExactlyOneScrubScheduleAndNoSettingInAUnitFile(t *testing.T) {
 	}
 	run := byID["scrub-run"]
 	args, _ := run["run"].([]any)
-	if run["type"] != "process" || run["name"] != "zfs-mesh-scrub" || run["schedule"] != "*/15 * * * *" || run["user"] != nil ||
+	if run["type"] != "process" || run["name"] != "zfs-mesh-scrub" || run["schedule"] != "0,15,30,45 * * * *" || run["user"] != nil ||
 		len(args) != 2 || args[1] != "scrub-run" {
 		t.Errorf("the scheduled run: %v", run)
 	}
+	// The node-engine writes a cron step ("*/15") as a calendar systemd refuses ("*:*/15"), and the timer never
+	// starts (novox/hq issue 1979, on the home server 2026-11-12). A list of minutes is written as a calendar
+	// systemd takes ("*-*-* *:0,15,30,45:00"), so the schedule names its minutes and never a step.
+	if s, _ := run["schedule"].(string); strings.Contains(s, "/") {
+		t.Errorf("the scheduled run's schedule %q uses a step, which the node-engine writes as a calendar systemd refuses", s)
+	}
 	if ScrubTimer != run["name"].(string)+".timer" || ScrubService != run["name"].(string)+".service" {
 		t.Errorf("the tools read %s and %s; the node-engine names them after %v", ScrubTimer, ScrubService, run["name"])
 	}
diff --git a/modules/zfs/module.json b/modules/zfs/module.json
index c109320a6..195263374 100644
--- a/modules/zfs/module.json
+++ b/modules/zfs/module.json
@@ -195,7 +195,7 @@
         "./zfs-tools",
         "scrub-run"
       ],
-      "schedule": "*/15 * * * *"
+      "schedule": "0,15,30,45 * * * *"
     },
     {
       "id": "distribution-weekly",