diff --git a/include/rt_names.h b/include/rt_names.h
index e5dbd45..37adbd3 100644
--- a/include/rt_names.h
+++ b/include/rt_names.h
@@ -3,29 +3,30 @@
 
 #include <asm/types.h>
 
-char* rtnl_rtprot_n2a(int id, char *buf, int len);
-char* rtnl_rtscope_n2a(int id, char *buf, int len);
-char* rtnl_rttable_n2a(__u32 id, char *buf, int len);
-char* rtnl_rtrealm_n2a(int id, char *buf, int len);
-char* rtnl_dsfield_n2a(int id, char *buf, int len);
-int rtnl_rtprot_a2n(__u32 *id, char *arg);
-int rtnl_rtscope_a2n(__u32 *id, char *arg);
-int rtnl_rttable_a2n(__u32 *id, char *arg);
-int rtnl_rtrealm_a2n(__u32 *id, char *arg);
-int rtnl_dsfield_a2n(__u32 *id, char *arg);
-int rtnl_group_a2n(int *id, char *arg);
+const char *rtnl_rtprot_n2a(int id, char *buf, int len);
+const char *rtnl_rtscope_n2a(int id, char *buf, int len);
+const char *rtnl_rttable_n2a(__u32 id, char *buf, int len);
+const char *rtnl_rtrealm_n2a(int id, char *buf, int len);
+const char *rtnl_dsfield_n2a(int id, char *buf, int len);
+
+int rtnl_rtprot_a2n(__u32 *id, const char *arg);
+int rtnl_rtscope_a2n(__u32 *id, const char *arg);
+int rtnl_rttable_a2n(__u32 *id, const char *arg);
+int rtnl_rtrealm_a2n(__u32 *id, const char *arg);
+int rtnl_dsfield_a2n(__u32 *id, const char *arg);
+int rtnl_group_a2n(int *id, const char *arg);
 
 const char *inet_proto_n2a(int proto, char *buf, int len);
-int inet_proto_a2n(char *buf);
+int inet_proto_a2n(const char *buf);
 
 
 const char * ll_type_n2a(int type, char *buf, int len);
-
-const char *ll_addr_n2a(unsigned char *addr, int alen, int type, char *buf, int blen);
-int ll_addr_a2n(char *lladdr, int len, char *arg);
+const char *ll_addr_n2a(unsigned char *addr, int alen,
+			int type, char *buf, int blen);
+int ll_addr_a2n(char *lladdr, int len, const char *arg);
 
 const char * ll_proto_n2a(unsigned short id, char *buf, int len);
-int ll_proto_a2n(unsigned short *id, char *buf);
+int ll_proto_a2n(unsigned short *id, const char *buf);
 
 
 #endif
diff --git a/lib/inet_proto.c b/lib/inet_proto.c
index a55e0e7..57a8351 100644
--- a/lib/inet_proto.c
+++ b/lib/inet_proto.c
@@ -20,9 +20,10 @@
 #include <netdb.h>
 #include <string.h>
 
+#include "rt_names.h"
 #include "utils.h"
 
-char *inet_proto_n2a(int proto, char *buf, int len)
+const char *inet_proto_n2a(int proto, char *buf, int len)
 {
 	static char ncache[16];
 	static int icache = -1;
@@ -42,7 +43,7 @@
 	return buf;
 }
 
-int inet_proto_a2n(char *buf)
+int inet_proto_a2n(const char *buf)
 {
 	static char ncache[16];
 	static int icache = -1;
diff --git a/lib/ll_addr.c b/lib/ll_addr.c
index f558050..c12ab07 100644
--- a/lib/ll_addr.c
+++ b/lib/ll_addr.c
@@ -57,7 +57,7 @@
 }
 
 /*NB: lladdr is char * (rather than u8 *) because sa_data is char * (1003.1g) */
-int ll_addr_a2n(char *lladdr, int len, char *arg)
+int ll_addr_a2n(char *lladdr, int len, const char *arg)
 {
 	if (strchr(arg, '.')) {
 		inet_prefix pfx;
diff --git a/lib/ll_proto.c b/lib/ll_proto.c
index 3337b14..3aa8252 100644
--- a/lib/ll_proto.c
+++ b/lib/ll_proto.c
@@ -100,10 +100,10 @@
         return buf;
 }
 
-int ll_proto_a2n(unsigned short *id, char *buf)
+int ll_proto_a2n(unsigned short *id, const char *buf)
 {
         int i;
-        for (i=0; i<sizeof(llproto_names)/sizeof(llproto_names[0]); i++) {
+        for (i=0; i < sizeof(llproto_names)/sizeof(llproto_names[0]); i++) {
                  if (strcasecmp(llproto_names[i].name, buf) == 0) {
 			 *id = htons(llproto_names[i].id);
 			 return 0;
diff --git a/lib/rt_names.c b/lib/rt_names.c
index 52ecdb2..02f1417 100644
--- a/lib/rt_names.c
+++ b/lib/rt_names.c
@@ -29,12 +29,12 @@
 
 struct rtnl_hash_entry {
 	struct rtnl_hash_entry *next;
-	char *			name;
+	const char *		name;
 	unsigned int		id;
 };
 
 static void
-rtnl_hash_initialize(char *file, struct rtnl_hash_entry **hash, int size)
+rtnl_hash_initialize(const char *file, struct rtnl_hash_entry **hash, int size)
 {
 	struct rtnl_hash_entry *entry;
 	char buf[512];
@@ -73,7 +73,7 @@
 	fclose(fp);
 }
 
-static void rtnl_tab_initialize(char *file, char **tab, int size)
+static void rtnl_tab_initialize(const char *file, char **tab, int size)
 {
 	char buf[512];
 	FILE *fp;
@@ -127,7 +127,6 @@
 };
 
 
-
 static int rtnl_rtprot_init;
 
 static void rtnl_rtprot_initialize(void)
@@ -137,10 +136,10 @@
 			    rtnl_rtprot_tab, 256);
 }
 
-char * rtnl_rtprot_n2a(int id, char *buf, int len)
+const char * rtnl_rtprot_n2a(int id, char *buf, int len)
 {
 	if (id<0 || id>=256) {
-		snprintf(buf, len, "%d", id);
+		snprintf(buf, len, "%u", id);
 		return buf;
 	}
 	if (!rtnl_rtprot_tab[id]) {
@@ -149,11 +148,11 @@
 	}
 	if (rtnl_rtprot_tab[id])
 		return rtnl_rtprot_tab[id];
-	snprintf(buf, len, "%d", id);
+	snprintf(buf, len, "%u", id);
 	return buf;
 }
 
-int rtnl_rtprot_a2n(__u32 *id, char *arg)
+int rtnl_rtprot_a2n(__u32 *id, const char *arg)
 {
 	static char *cache = NULL;
 	static unsigned long res;
@@ -186,7 +185,6 @@
 }
 
 
-
 static char * rtnl_rtscope_tab[256] = {
 	"global",
 };
@@ -204,7 +202,7 @@
 			    rtnl_rtscope_tab, 256);
 }
 
-char * rtnl_rtscope_n2a(int id, char *buf, int len)
+const char *rtnl_rtscope_n2a(int id, char *buf, int len)
 {
 	if (id<0 || id>=256) {
 		snprintf(buf, len, "%d", id);
@@ -220,9 +218,9 @@
 	return buf;
 }
 
-int rtnl_rtscope_a2n(__u32 *id, char *arg)
+int rtnl_rtscope_a2n(__u32 *id, const char *arg)
 {
-	static char *cache = NULL;
+	static const char *cache = NULL;
 	static unsigned long res;
 	char *end;
 	int i;
@@ -253,7 +251,6 @@
 }
 
 
-
 static char * rtnl_rtrealm_tab[256] = {
 	"unknown",
 };
@@ -267,7 +264,7 @@
 			    rtnl_rtrealm_tab, 256);
 }
 
-char * rtnl_rtrealm_n2a(int id, char *buf, int len)
+const char *rtnl_rtrealm_n2a(int id, char *buf, int len)
 {
 	if (id<0 || id>=256) {
 		snprintf(buf, len, "%d", id);
@@ -284,7 +281,7 @@
 }
 
 
-int rtnl_rtrealm_a2n(__u32 *id, char *arg)
+int rtnl_rtrealm_a2n(__u32 *id, const char *arg)
 {
 	static char *cache = NULL;
 	static unsigned long res;
@@ -336,7 +333,7 @@
 			     rtnl_rttable_hash, 256);
 }
 
-char * rtnl_rttable_n2a(__u32 id, char *buf, int len)
+const char * rtnl_rttable_n2a(__u32 id, char *buf, int len)
 {
 	struct rtnl_hash_entry *entry;
 
@@ -355,9 +352,9 @@
 	return buf;
 }
 
-int rtnl_rttable_a2n(__u32 *id, char *arg)
+int rtnl_rttable_a2n(__u32 *id, const char *arg)
 {
-	static char *cache = NULL;
+	static const char *cache = NULL;
 	static unsigned long res;
 	struct rtnl_hash_entry *entry;
 	char *end;
@@ -404,7 +401,7 @@
 			    rtnl_rtdsfield_tab, 256);
 }
 
-char * rtnl_dsfield_n2a(int id, char *buf, int len)
+const char *rtnl_dsfield_n2a(int id, char *buf, int len)
 {
 	if (id<0 || id>=256) {
 		snprintf(buf, len, "%d", id);
@@ -421,7 +418,7 @@
 }
 
 
-int rtnl_dsfield_a2n(__u32 *id, char *arg)
+int rtnl_dsfield_a2n(__u32 *id, const char *arg)
 {
 	static char *cache = NULL;
 	static unsigned long res;
@@ -469,9 +466,9 @@
 			     rtnl_group_hash, 256);
 }
 
-int rtnl_group_a2n(int *id, char *arg)
+int rtnl_group_a2n(int *id, const char *arg)
 {
-	static char *cache = NULL;
+	static const char *cache = NULL;
 	static unsigned long res;
 	struct rtnl_hash_entry *entry;
 	char *end;