diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index 3c3bb18..6c4f5ea 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -32,6 +32,11 @@
 #define RT6_LOOKUP_F_SRCPREF_PUBLIC	0x00000010
 #define RT6_LOOKUP_F_SRCPREF_COA	0x00000020
 
+/* We do not (yet ?) support IPv6 jumbograms (RFC 2675)
+ * Unlike IPv4, hdr->seg_len doesn't include the IPv6 header
+ */
+#define IP6_MAX_MTU (0xFFFF + sizeof(struct ipv6hdr))
+
 /*
  * rt6_srcprefs2flags() and rt6_flags2srcprefs() translate
  * between IPV6_ADDR_PREFERENCES socket option values