diff --git a/src/libs/compat/freebsd_network/compat/sys/callout.h b/src/libs/compat/freebsd_network/compat/sys/callout.h
index 8084c6750e..f6c5a67d02 100644
--- a/src/libs/compat/freebsd_network/compat/sys/callout.h
+++ b/src/libs/compat/freebsd_network/compat/sys/callout.h
@@ -19,6 +19,7 @@ struct callout {
 	int					c_flags;
 };
 
+#define CALLOUT_MPSAFE	0x0001
 
 void callout_init_mtx(struct callout *c, struct mtx *mutex, int flags);
 int	callout_reset(struct callout *, int, void (*)(void *), void *);