Missing dependency spotted by Robert P Day.
diff --git a/networking/Config.in b/networking/Config.in
index 7820c9a..0a57170 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -260,7 +260,7 @@
 config CONFIG_FEATURE_IFUPDOWN_IPV6
 	bool "  Enable support for IPv6"
 	default n
-	depends on CONFIG_IFUPDOWN
+	depends on CONFIG_IFUPDOWN && CONFIG_FEATURE_IPV6
 	help
 	  If you need support for IPv6, turn this option on.
 
@@ -688,8 +688,6 @@
 	help
 	  Support IPv6 address literal notation in URLs.
 
-source networking/udhcp/Config.in
-
 config CONFIG_ZCIP
 	bool "zcip"
 	default n