diff --git a/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go b/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
index ca46828f9..7c40247b0 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go
@@ -262,9 +262,9 @@ func (s *OutputRoomEvent) updateStateEvent(event gomatrixserverlib.Event) (gomat
 	}
 
 	prev := types.PrevEventRef{
-		PrevContent: prevEvent.Content(),
-		PrevID:      prevEvent.EventID(),
-		PrevSender:  prevEvent.Sender(),
+		PrevContent:   prevEvent.Content(),
+		ReplacesState: prevEvent.EventID(),
+		PrevSender:    prevEvent.Sender(),
 	}
 
 	return event.SetUnsigned(prev)
diff --git a/src/github.com/matrix-org/dendrite/syncapi/types/types.go b/src/github.com/matrix-org/dendrite/syncapi/types/types.go
index cf737a408..f710c6d5d 100644
--- a/src/github.com/matrix-org/dendrite/syncapi/types/types.go
+++ b/src/github.com/matrix-org/dendrite/syncapi/types/types.go
@@ -31,9 +31,9 @@ func (sp StreamPosition) String() string {
 
 // PrevEventRef represents a reference to a previous event in a state event upgrade
 type PrevEventRef struct {
-	PrevContent json.RawMessage `json:"prev_content"`
-	PrevID      string          `json:"replaces_state"`
-	PrevSender  string          `json:"prev_sender"`
+	PrevContent   json.RawMessage `json:"prev_content"`
+	ReplacesState string          `json:"replaces_state"`
+	PrevSender    string          `json:"prev_sender"`
 }
 
 // Response represents a /sync API response. See https://matrix.org/docs/spec/client_server/r0.2.0.html#get-matrix-client-r0-sync