diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index cef201e48966..4ea64fa0ec07 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -551,6 +551,7 @@ struct ptrace_args {
 	copyout(k ## 32, u, s ## 32) : \
 	copyout(k, u, s)
 #else
+#define	BZERO(a, s)		bzero(a, s)
 #define	COPYIN(u, k, s)		copyin(u, k, s)
 #define	COPYOUT(k, u, s)	copyout(k, u, s)
 #endif