diff --git a/support/nfsidmap/gums.c b/support/nfsidmap/gums.c
index 1d6eb318..e94a4c50 100644
--- a/support/nfsidmap/gums.c
+++ b/support/nfsidmap/gums.c
@@ -475,7 +475,7 @@ static int translate_to_uid(char *local_uid, uid_t *uid, uid_t *gid)
 	int ret = -1;
 	struct passwd *pw = NULL;
 	struct pwbuf *buf = NULL;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 
 	buf = malloc(sizeof(*buf) + buflen);
 	if (buf == NULL)
@@ -501,7 +501,7 @@ static int translate_to_gid(char *local_gid, uid_t *gid)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf = NULL;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int ret = -1;
 
 	do {
diff --git a/support/nfsidmap/libnfsidmap.c b/support/nfsidmap/libnfsidmap.c
index f8c36480..e1475879 100644
--- a/support/nfsidmap/libnfsidmap.c
+++ b/support/nfsidmap/libnfsidmap.c
@@ -457,7 +457,7 @@ int nfs4_init_name_mapping(char *conffile)
 
 	nobody_user = conf_get_str("Mapping", "Nobody-User");
 	if (nobody_user) {
-		size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+		size_t buflen = get_pwnam_buflen();
 		struct passwd *buf;
 		struct passwd *pw = NULL;
 		int err;
@@ -478,7 +478,7 @@ int nfs4_init_name_mapping(char *conffile)
 
 	nobody_group = conf_get_str("Mapping", "Nobody-Group");
 	if (nobody_group) {
-		size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+		size_t buflen = get_grnam_buflen();
 		struct group *buf;
 		struct group *gr = NULL;
 		int err;
diff --git a/support/nfsidmap/nfsidmap_common.c b/support/nfsidmap/nfsidmap_common.c
index 4d2cb14f..310c68f0 100644
--- a/support/nfsidmap/nfsidmap_common.c
+++ b/support/nfsidmap/nfsidmap_common.c
@@ -116,3 +116,19 @@ int get_reformat_group(void)
 
 	return reformat_group;
 }
+
+size_t get_pwnam_buflen(void)
+{
+	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	if (buflen == -1)
+		buflen = 16384;
+	return buflen;
+}
+
+size_t get_grnam_buflen(void)
+{
+	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	if (buflen == -1)
+		buflen = 16384;
+	return buflen;
+}
diff --git a/support/nfsidmap/nfsidmap_private.h b/support/nfsidmap/nfsidmap_private.h
index a5cb6dda..234ca9d4 100644
--- a/support/nfsidmap/nfsidmap_private.h
+++ b/support/nfsidmap/nfsidmap_private.h
@@ -40,6 +40,8 @@ struct conf_list *get_local_realms(void);
 void free_local_realms(void);
 int get_nostrip(void);
 int get_reformat_group(void);
+size_t get_pwnam_buflen(void);
+size_t get_grnam_buflen(void);
 
 typedef enum {
 	IDTYPE_USER = 1,
diff --git a/support/nfsidmap/nss.c b/support/nfsidmap/nss.c
index 0f43076e..3fc045dc 100644
--- a/support/nfsidmap/nss.c
+++ b/support/nfsidmap/nss.c
@@ -91,7 +91,7 @@ static int nss_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
 	struct passwd *pw = NULL;
 	struct passwd pwbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	int err = -ENOMEM;
 
 	buf = malloc(buflen);
@@ -119,7 +119,7 @@ static int nss_gid_to_name(gid_t gid, char *domain, char *name, size_t len)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err;
 
 	if (domain == NULL)
@@ -192,7 +192,7 @@ static struct passwd *nss_getpwnam(const char *name, const char *domain,
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	int err = ENOMEM;
 
@@ -301,7 +301,7 @@ static int _nss_name_to_gid(char *name, gid_t *gid, int dostrip)
 	struct group *gr = NULL;
 	struct group grbuf;
 	char *buf, *domain;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err = -EINVAL;
 	char *localname = NULL;
 	char *ref_name = NULL;
diff --git a/support/nfsidmap/regex.c b/support/nfsidmap/regex.c
index 8424179f..ea094b95 100644
--- a/support/nfsidmap/regex.c
+++ b/support/nfsidmap/regex.c
@@ -46,6 +46,7 @@
 
 #include "nfsidmap.h"
 #include "nfsidmap_plugin.h"
+#include "nfsidmap_private.h"
 
 #define CONFIG_GET_STRING nfsidmap_config_get
 extern const char *nfsidmap_config_get(const char *, const char *);
@@ -95,7 +96,7 @@ static struct passwd *regex_getpwnam(const char *name, const char *UNUSED(domain
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	size_t namelen;
 	int err;
@@ -175,7 +176,7 @@ static struct group *regex_getgrnam(const char *name, const char *UNUSED(domain)
 {
 	struct group *gr;
 	struct grbuf *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	char *localgroup;
 	char *groupname;
 	size_t namelen;
@@ -366,7 +367,7 @@ static int regex_uid_to_name(uid_t uid, char *domain, char *name, size_t len)
 	struct passwd *pw = NULL;
 	struct passwd pwbuf;
 	char *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	int err = -ENOMEM;
 
 	buf = malloc(buflen);
@@ -392,7 +393,7 @@ static int regex_gid_to_name(gid_t gid, char *UNUSED(domain), char *name, size_t
 	struct group grbuf;
 	char *buf;
     const char *name_prefix;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	int err;
     char * groupname = NULL;
 
diff --git a/support/nfsidmap/static.c b/support/nfsidmap/static.c
index 8ac4a398..395cac06 100644
--- a/support/nfsidmap/static.c
+++ b/support/nfsidmap/static.c
@@ -44,6 +44,7 @@
 #include "conffile.h"
 #include "nfsidmap.h"
 #include "nfsidmap_plugin.h"
+#include "nfsidmap_private.h"
 
 /*
  * Static Translation Methods
@@ -98,7 +99,7 @@ static struct passwd *static_getpwnam(const char *name,
 {
 	struct passwd *pw;
 	struct pwbuf *buf;
-	size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+	size_t buflen = get_pwnam_buflen();
 	char *localname;
 	int err;
 
@@ -149,7 +150,7 @@ static struct group *static_getgrnam(const char *name,
 {
 	struct group *gr;
 	struct grbuf *buf;
-	size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX);
+	size_t buflen = get_grnam_buflen();
 	char *localgroup;
 	int err;
 
