diff --git a/src/core/unit.c b/src/core/unit.c
index 3f616e7acf..279619f039 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -5803,9 +5803,11 @@ bool unit_needs_console(Unit *u) {
         return exec_context_may_touch_console(ec);
 }
 
-const char *unit_label_path(Unit *u) {
+const char *unit_label_path(const Unit *u) {
         const char *p;
 
+        assert(u);
+
         /* Returns the file system path to use for MAC access decisions, i.e. the file to read the SELinux label off
          * when validating access checks. */
 
diff --git a/src/core/unit.h b/src/core/unit.h
index 38d681dfb8..999c7a7d83 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -842,7 +842,7 @@ int unit_warn_leftover_processes(Unit *u);
 
 bool unit_needs_console(Unit *u);
 
-const char *unit_label_path(Unit *u);
+const char *unit_label_path(const Unit *u);
 
 int unit_pid_attachable(Unit *unit, pid_t pid, sd_bus_error *error);