diff --git a/bip-0070.mediawiki b/bip-0070.mediawiki
index accd12bb..fecbbabf 100644
--- a/bip-0070.mediawiki
+++ b/bip-0070.mediawiki
@@ -47,6 +47,8 @@ PaymentRequest message:
 
 ==Messages==
 
+The Protocol Buffer messages are defined here: https://raw.github.com/bitcoin/bitcoin/master/src/qt/paymentrequest.proto
+
 ===Output===
 
 Outputs are used in PaymentRequest messages to specify where a payment (or