diff --git a/src/journal/journald-server.h b/src/journal/journald-server.h
index 1f274ecf26..5de44d76b4 100644
--- a/src/journal/journald-server.h
+++ b/src/journal/journald-server.h
@@ -189,7 +189,7 @@ struct Server {
 #define N_IOVEC_PAYLOAD_FIELDS 15
 
 void server_dispatch_message(Server *s, struct iovec *iovec, size_t n, size_t m, ClientContext *c, const struct timeval *tv, int priority, pid_t object_pid);
-void server_driver_message(Server *s, pid_t object_pid, const char *message_id, const char *format, ...) _sentinel_;
+void server_driver_message(Server *s, pid_t object_pid, const char *message_id, const char *format, ...) _sentinel_ _printf_(4,0);
 
 /* gperf lookup function */
 const struct ConfigPerfItem* journald_gperf_lookup(const char *key, GPERF_LEN_TYPE length);