Index: sys/kern/tty_info.c
===================================================================
--- sys/kern/tty_info.c
+++ sys/kern/tty_info.c
@@ -239,7 +239,11 @@
 }
 
 #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)