diff --git a/core/contiki-default-conf.h b/core/contiki-default-conf.h
index 1e5c2f5c9..b3780a952 100644
--- a/core/contiki-default-conf.h
+++ b/core/contiki-default-conf.h
@@ -114,7 +114,7 @@
 /* UIP_CONF_IPV6 specifies whether or not IPv6 should be used. If IPv6
    is not used, IPv4 is used instead. */
 #ifndef UIP_CONF_IPV6
-#define UIP_CONF_IPV6 1
+#define UIP_CONF_IPV6 0
 #endif /* UIP_CONF_IPV6 */
 
 /* UIP_CONF_BUFFER_SIZE specifies how much memory should be reserved