diff --git a/sys/kern/tty_info.c b/sys/kern/tty_info.c
index 237aa47a18da..be6de114bdfd 100644
--- a/sys/kern/tty_info.c
+++ b/sys/kern/tty_info.c
@@ -239,7 +239,11 @@ sbuf_tty_drain(void *a, const char *d, int len)
 }
 
 #ifdef STACK
+#ifdef INVARIANTS
 static int tty_info_kstacks = STACK_SBUF_FMT_COMPACT;
+#else
+static int tty_info_kstacks = STACK_SBUF_FMT_NONE;
+#endif
 
 static int
 sysctl_tty_info_kstacks(SYSCTL_HANDLER_ARGS)