diff --git a/examples/er-rest-example/project-conf.h b/examples/er-rest-example/project-conf.h
index 53662619a..3d894a5d4 100644
--- a/examples/er-rest-example/project-conf.h
+++ b/examples/er-rest-example/project-conf.h
@@ -60,6 +60,9 @@
 #undef NETSTACK_CONF_RDC
 #define NETSTACK_CONF_RDC              nullrdc_driver
 
+#undef RPL_CONF_MAX_DAG_PER_INSTANCE
+#define RPL_CONF_MAX_DAG_PER_INSTANCE     1
+
 /* Disabling TCP on CoAP nodes. */
 #undef UIP_CONF_TCP
 #define UIP_CONF_TCP                   0
@@ -93,6 +96,10 @@
 #undef COAP_PROXY_OPTION_PROCESSING
 #define COAP_PROXY_OPTION_PROCESSING   0
 
+/* Turn of DAO ACK to make code smaller */
+#undef RPL_CONF_WITH_DAO_ACK
+#define RPL_CONF_WITH_DAO_ACK          0
+
 /* Enable client-side support for COAP observe */
 #define COAP_OBSERVE_CLIENT 1
 #endif /* __PROJECT_ERBIUM_CONF_H__ */