diff --git a/crates/ruma-events/src/call/member.rs b/crates/ruma-events/src/call/member.rs
index 3bb34371..9b8b30bd 100644
--- a/crates/ruma-events/src/call/member.rs
+++ b/crates/ruma-events/src/call/member.rs
@@ -176,12 +176,6 @@ pub struct MembershipInit {
     /// `MIN(content.created_ts, event.origin_server_ts)`
     pub expires: Duration,
 
-    /// Stores a copy of the `origin_server_ts` of the initial session event.
-    ///
-    /// If the membership is updated this field will be used to track to
-    /// original `origin_server_ts`.
-    pub created_ts: Option<MilliSecondsSinceUnixEpoch>,
-
     /// A list of the focuses (foci) in use for this membership.
     pub foci_active: Vec<Focus>,
 
@@ -195,15 +189,8 @@ pub struct MembershipInit {
 
 impl From<MembershipInit> for Membership {
     fn from(init: MembershipInit) -> Self {
-        let MembershipInit {
-            application,
-            device_id,
-            expires,
-            created_ts,
-            foci_active,
-            membership_id,
-        } = init;
-        Self { application, device_id, expires, created_ts, foci_active, membership_id }
+        let MembershipInit { application, device_id, expires, foci_active, membership_id } = init;
+        Self { application, device_id, expires, created_ts: None, foci_active, membership_id }
     }
 }