diff --git a/bgpd/bgp_main.c b/bgpd/bgp_main.c
index a4cd9ab..05ecb72 100644
--- a/bgpd/bgp_main.c
+++ b/bgpd/bgp_main.c
@@ -91,7 +91,7 @@
 char *config_file = NULL;
 
 /* Process ID saved for use by init system */
-char *pid_file = PATH_BGPD_PID;
+const char *pid_file = PATH_BGPD_PID;
 
 /* VTY port number and address.  */
 int vty_port = BGP_VTY_PORT;