diff --git a/nasl/nasl_packet_forgery_v6.c b/nasl/nasl_packet_forgery_v6.c
index a93302c..c255b0f 100644
--- a/nasl/nasl_packet_forgery_v6.c
+++ b/nasl/nasl_packet_forgery_v6.c
@@ -75,6 +75,7 @@
 #define UNFIX(n) ntohs (n)
 #endif
 
+#define TCP_MSS_DESIRED		1220U   /* IPv6 (tunneled), EDNS0 (RFC3226) */
 /*--------------[ cksum ]-----------------------------------------*/
 
 /*
diff --git a/nasl/nasl_packet_forgery.c b/nasl/nasl_packet_forgery.c
index 7d185df..c0a5ffb 100644
--- a/nasl/nasl_packet_forgery.c
+++ b/nasl/nasl_packet_forgery.c
@@ -52,6 +52,7 @@
 #define UNFIX(n) ntohs (n)
 #endif
 
+#define TCP_MSS_DEFAULT		 536U	/* IPv4 (RFC1122, RFC2581) */
 /*--------------[ cksum ]-----------------------------------------*/
 
 /*