diff --git a/examples/ipv6/json-ws/project-conf.h b/examples/ipv6/json-ws/project-conf.h
index 948724f7e..1135d7dd1 100644
--- a/examples/ipv6/json-ws/project-conf.h
+++ b/examples/ipv6/json-ws/project-conf.h
@@ -38,13 +38,10 @@
 #define JSON_WS_CONF_CALLBACK_PORT  80
 #define JSON_WS_CONF_CALLBACK_INTERVAL 120
 
-#undef WEBSERVER_CONF_INBUF_SIZE
 #define WEBSERVER_CONF_INBUF_SIZE 200
 
-#undef WEBSERVER_CONF_OUTBUF_SIZE
 #define WEBSERVER_CONF_OUTBUF_SIZE (UIP_TCP_MSS + 20 + 80)
 
-#undef WEBSERVER_CONF_CFS_CONNS
 #define WEBSERVER_CONF_CFS_CONNS 3
 
 #endif /* PROJECT_CONF_H_ */