diff --git a/docs/api/messages.md b/docs/api/messages.md
index e85e548..0fce04e 100644
--- a/docs/api/messages.md
+++ b/docs/api/messages.md
@@ -30,6 +30,7 @@ Heartbeat messages are posted to the heartbeat channel periodically.
 | blocktimestamp | time              | Block timestamp                                                   |
 | receipt        | ActionReceipt     | Action receipt                                                    |
 | receiver       | string            | Receiver account                                                  |
+| first_receiver | bool              | True if receiver is the first account to get notified             |
 | contract       | string            | Contract account                                                  |
 | action         | string            | What action was executed on the contract                          |
 | data           | any               | Contract specific data (decoded using the contracts abi)          |
@@ -84,4 +85,4 @@ Heartbeat messages are posted to the heartbeat channel periodically.
 | -------- | ------------- | --------------------------------- |
 | present  | bool          | -                                 |
 | data     | any           | Decoded data                      |
-| raw_data | base64_string | Raw data in base64 encoded string |
\ No newline at end of file
+| raw_data | base64_string | Raw data in base64 encoded string |