Deprecate using NET_C without HAVE_IPV6
diff --git a/configs/config-ccm-psk-tls1_2.h b/configs/config-ccm-psk-tls1_2.h
index 776179d..4a3ebb1 100644
--- a/configs/config-ccm-psk-tls1_2.h
+++ b/configs/config-ccm-psk-tls1_2.h
@@ -12,7 +12,7 @@
 #define POLARSSL_CONFIG_H
 
 /* System support */
-//#define POLARSSL_HAVE_IPV6 /* Optional */
+#define POLARSSL_HAVE_IPV6 /* Now mandatory for NET_C */
 //#define POLARSSL_HAVE_TIME /* Optionally used in Hello messages */
 /* Other POLARSSL_HAVE_XXX flags irrelevant for this configuration */