diff --git a/artio-codecs/src/main/java/uk/co/real_logic/artio/fixp/FixPConnectionHandler.java b/artio-codecs/src/main/java/uk/co/real_logic/artio/fixp/FixPConnectionHandler.java
index 5174ffabe8..f2c5bc1072 100644
--- a/artio-codecs/src/main/java/uk/co/real_logic/artio/fixp/FixPConnectionHandler.java
+++ b/artio-codecs/src/main/java/uk/co/real_logic/artio/fixp/FixPConnectionHandler.java
@@ -105,6 +105,14 @@ default Action onRetransmitRequest(
         return Action.CONTINUE;
     }
 
+    default Action onEstablishmentAck(
+        final FixPConnection connection, long previousUuid, long previousSeqNo, long uuid, long lastuuid,
+        long nextSeqNo)
+    {
+        // default for backwards compatibility.
+        return Action.CONTINUE;
+    }
+
     /**
      * Callback triggered by a timeout on a retransmit request. See
      * {@link Builder#retransmitNotificationTimeoutInMs(int)} for details.
diff --git a/artio-ilink3-impl/src/main/java/uk/co/real_logic/artio/library/InternalILink3Connection.java b/artio-ilink3-impl/src/main/java/uk/co/real_logic/artio/library/InternalILink3Connection.java
index 0b5c58e906..88c9300520 100644
--- a/artio-ilink3-impl/src/main/java/uk/co/real_logic/artio/library/InternalILink3Connection.java
+++ b/artio-ilink3-impl/src/main/java/uk/co/real_logic/artio/library/InternalILink3Connection.java
@@ -775,6 +775,8 @@ public Action onEstablishmentAck(
         initiateReply = null;
         nextReceiveMessageTimeInMs = nextRecvTimeoutInMs();
 
+        handler.onEstablishmentAck(this, previousUUID, previousSeqNo, uUID, lastUuid, nextSeqNo);
+
         if (previousUUID == lastUuid)
         {
             if (previousSeqNo > lastConnectionLastReceivedSequenceNumber)