diff --git a/client.go b/client.go
index 71c3fb18..edeab732 100644
--- a/client.go
+++ b/client.go
@@ -754,7 +754,7 @@ func (req *ReqSync) BuildQuery() map[string]string {
 		query["full_state"] = "true"
 	}
 	if req.UseStateAfter {
-		query["org.matrix.msc4222.use_state_after"] = "true"
+		query["use_state_after"] = "true"
 	}
 	if req.BeeperStreaming {
 		query["com.beeper.streaming"] = "true"
diff --git a/responses.go b/responses.go
index 8ab78373..e2627724 100644
--- a/responses.go
+++ b/responses.go
@@ -397,7 +397,7 @@ type BeeperInboxPreviewEvent struct {
 type SyncJoinedRoom struct {
 	Summary     LazyLoadSummary `json:"summary"`
 	State       SyncEventsList  `json:"state"`
-	StateAfter  *SyncEventsList `json:"org.matrix.msc4222.state_after,omitempty"`
+	StateAfter  *SyncEventsList `json:"state_after,omitempty"`
 	Timeline    SyncTimeline    `json:"timeline"`
 	Ephemeral   SyncEventsList  `json:"ephemeral"`
 	AccountData SyncEventsList  `json:"account_data"`