diff --git a/bgpd/bgp_regex.c b/bgpd/bgp_regex.c
index a6b6598..be84d40 100644
--- a/bgpd/bgp_regex.c
+++ b/bgpd/bgp_regex.c
@@ -34,7 +34,7 @@
    (^|[,{}() ]|$) */
 
 regex_t *
-bgp_regcomp (char *regstr)
+bgp_regcomp (const char *regstr)
 {
   /* Convert _ character to generic regular expression. */
   int i, j;