diff --git a/server/cmd/echolot-server/main.go b/server/cmd/echolot-server/main.go
index 8e923c2..43b0c9f 100644
--- a/server/cmd/echolot-server/main.go
+++ b/server/cmd/echolot-server/main.go
@@ -73,6 +73,26 @@ func run() error {
 
 	switch {
 	case actions.Help:
+		// Compatibility shim for one release.
+		//
+		// Serving became an explicit verb, but self-update is run by the *old* binary — so the
+		// repair added to the updater cannot fix the very update that installs the new one. A
+		// unit written before this change starts us with no arguments, and without this branch
+		// the service would simply stop working, unattended, on a host nobody is watching.
+		//
+		// Only when systemd started us: INVOCATION_ID is set by systemd for every service
+		// invocation and by nothing else, so a person at a terminal still gets usage. Remove
+		// this once no deployment predates --serve.
+		if os.Getenv("INVOCATION_ID") != "" {
+			slog.Warn("started by systemd with no verb — this unit predates --serve; " +
+				"repairing it and serving anyway")
+			if repaired, err := system.RepairExecStart(); err != nil {
+				slog.Error("could not repair the unit; fix ExecStart by hand", "err", err)
+			} else if repaired {
+				slog.Info("systemd unit updated to pass --serve")
+			}
+			return serve(cfg)
+		}
 		config.Usage(os.Stderr)
 		os.Exit(2)
 		return nil