diff --git a/examples/ipv6/rpl-border-router/border-router.c b/examples/ipv6/rpl-border-router/border-router.c
index 0a749dc71..6373d1e95 100644
--- a/examples/ipv6/rpl-border-router/border-router.c
+++ b/examples/ipv6/rpl-border-router/border-router.c
@@ -174,7 +174,7 @@ void
 request_prefix(void)
 {
   /* mess up uip_buf with a dirty request... */
-  uip_buf[0] = '!';
+  uip_buf[0] = '?';
   uip_buf[1] = 'P';
   uip_len = 2;
   slip_send();
diff --git a/tools/tunslip6.c b/tools/tunslip6.c
index 650f58b58..82ab3f433 100644
--- a/tools/tunslip6.c
+++ b/tools/tunslip6.c
@@ -210,7 +210,9 @@ serial_to_tun(FILE *inslip, int outfd)
 	  ssystem("ifconfig %s hw ether %s", tundev, &macs[6]);
           if (timestamp) stamptime();
 	  ssystem("ifconfig %s up", tundev);
-	} else if(uip.inbuf[1] == 'P') {
+	}
+      } else if(uip.inbuf[0] == '?') {
+	if(uip.inbuf[1] == 'P') {
           /* Prefix info requested */
           struct in6_addr addr;
 	  int i;