diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 488adf63..f398292d 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -2494,7 +2494,7 @@
  * network startup.
  */
 #if !defined LWIP_IPV6_SEND_ROUTER_SOLICIT || defined __DOXYGEN__
-#define LWIP_IPV6_SEND_ROUTER_SOLICIT   1
+#define LWIP_IPV6_SEND_ROUTER_SOLICIT   LWIP_IPV6
 #endif
 
 /**