diff --git a/DIFFERENCES.md b/DIFFERENCES.md
index c8568f93..f47c078f 100644
--- a/DIFFERENCES.md
+++ b/DIFFERENCES.md
@@ -51,3 +51,4 @@
 - Add basic cache eviction for true destinations when requests fail if we use a cached destination (e.g. a server has modified their well-known and we're still connecting to the old destination)
 - Only follow 6 redirects total in our default reqwest ClientBuilder
 - Generate passwords with 25 characters instead of 15
+- Add missing `reason` field to user ban events (`/ban`)
diff --git a/src/api/client_server/membership.rs b/src/api/client_server/membership.rs
index 2d31e36f..5c297948 100644
--- a/src/api/client_server/membership.rs
+++ b/src/api/client_server/membership.rs
@@ -259,6 +259,7 @@ pub async fn ban_user_route(body: Ruma<ban_user::v3::Request>) -> Result<ban_use
                 serde_json::from_str(event.content.get())
                     .map(|event: RoomMemberEventContent| RoomMemberEventContent {
                         membership: MembershipState::Ban,
+                        reason: event.reason,
                         ..event
                     })
                     .map_err(|_| Error::bad_database("Invalid member event in database."))