diff --git a/09-features.md b/09-features.md
index 4677b1111..8d3d025ea 100644
--- a/09-features.md
+++ b/09-features.md
@@ -24,6 +24,7 @@ The Context column decodes as follows:
 * `C`: presented in the `channel_announcement` message.
 * `C-`: presented in the `channel_announcement` message, but always odd (optional).
 * `C+`: presented in the `channel_announcement` message, but always even (required).
+* `9`: presented in [BOLT 11](11-payment-encoding.md) invoices.
 
 | Bits  | Name                             | Description                                               | Context  | Link                                  |
 |-------|----------------------------------|-----------------------------------------------------------|----------|---------------------------------------|
diff --git a/11-payment-encoding.md b/11-payment-encoding.md
index b03409311..e9a28770a 100644
--- a/11-payment-encoding.md
+++ b/11-payment-encoding.md
@@ -272,7 +272,8 @@ Don't be like the school of [Little Bobby Tables](https://xkcd.com/327/).
 ## Feature Bits
 
 Feature bits allow forward and backward compatibility, and follow the
-_it's ok to be odd_ rule.
+_it's ok to be odd_ rule.  Features appropriate for use in the `9` field
+are marked in [BOLT 9](09-features.md).
 
 The field is big-endian.  The least-significant bit is numbered 0,
 which is _even_, and the next most significant bit is numbered 1,