diff --git a/kea-multithreading-packet-processing-requirements.md b/kea-multithreading-packet-processing-requirements.md
index 0a115ba..055e953 100644
--- a/kea-multithreading-packet-processing-requirements.md
+++ b/kea-multithreading-packet-processing-requirements.md
@@ -4,6 +4,7 @@
 
 * It must not break the DHCP protocol (obviously)
 * Must compile and use supported dependencies on all supported platforms (obviously)
+* It MUST be supported by DHCPv4 and DHCPv6 servers
 * It must support MySql and PgSql back-ends
 * It must be configurable in the configuration file, at run-time using control channel commands or on the command line (still in discussion).
 * Should not have impact on the old server functionality if the feature is disabled