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