diff --git a/blah-types/src/lib.rs b/blah-types/src/lib.rs
index 18b93f4..a8efb75 100644
--- a/blah-types/src/lib.rs
+++ b/blah-types/src/lib.rs
@@ -329,6 +329,8 @@ pub struct RoomMetadata {
     /// This may or may not be a precise number.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub unseen_cnt: Option<u64>,
+    /// The member permission of current user in the room, or `None` if it is not a member.
+    /// Only available with authentication.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub member_permission: Option<MemberPermission>,
 }
diff --git a/docs/webapi.yaml b/docs/webapi.yaml
index 0442aa6..53f75c8 100644
--- a/docs/webapi.yaml
+++ b/docs/webapi.yaml
@@ -388,6 +388,9 @@ components:
             GET `/room?filter=unseen`.
           type: integer
           format: uint64
+        member_permission:
+          type: integer
+          format: int64
 
     RoomMetadata:
       type: object