diff --git a/sys/rpc/svc_auth_unix.c b/sys/rpc/svc_auth_unix.c
--- a/sys/rpc/svc_auth_unix.c
+++ b/sys/rpc/svc_auth_unix.c
@@ -50,9 +50,6 @@
 
 #include <rpc/rpc_com.h>
 
-#define MAX_MACHINE_NAME	255
-#define NGRPS			16
-
 /*
  * Unix longhand authenticator
  */
@@ -76,7 +73,7 @@
 	if (buf != NULL) {
 		time = IXDR_GET_UINT32(buf);
 		str_len = (size_t)IXDR_GET_UINT32(buf);
-		if (str_len > MAX_MACHINE_NAME) {
+		if (str_len > AUTH_SYS_MAX_HOSTNAME) {
 			stat = AUTH_BADCRED;
 			goto done;
 		}
@@ -85,7 +82,7 @@
 		xcr->cr_uid = IXDR_GET_UINT32(buf);
 		xcr->cr_gid = IXDR_GET_UINT32(buf);
 		supp_ngroups = (size_t)IXDR_GET_UINT32(buf);
-		if (supp_ngroups > NGRPS) {
+		if (supp_ngroups > AUTH_SYS_MAX_GROUPS) {
 			stat = AUTH_BADCRED;
 			goto done;
 		}