diff --git a/src/tty-ask-password-agent/tty-ask-password-agent.c b/src/tty-ask-password-agent/tty-ask-password-agent.c
index 1c1b95bef3..26c135a45f 100644
--- a/src/tty-ask-password-agent/tty-ask-password-agent.c
+++ b/src/tty-ask-password-agent/tty-ask-password-agent.c
@@ -666,6 +666,7 @@ static int ask_on_consoles(char *argv[]) {
         _cleanup_set_free_ Set *pids = NULL;
         int r;
 
+        assert(!arg_device);
         assert(argv);
 
         r = get_kernel_consoles(&consoles);