diff --git a/federationapi/routing/backfill.go b/federationapi/routing/backfill.go
index 62471b8a9..6f85ba4be 100644
--- a/federationapi/routing/backfill.go
+++ b/federationapi/routing/backfill.go
@@ -97,7 +97,10 @@ func Backfill(
 	}
 
 	var eventJSONs []json.RawMessage
-	for _, e := range gomatrixserverlib.ReverseTopologicalOrdering(evs) {
+	for _, e := range gomatrixserverlib.ReverseTopologicalOrdering(
+		evs,
+		gomatrixserverlib.TopologicalOrderByPrevEvents,
+	) {
 		eventJSONs = append(eventJSONs, e.JSON())
 	}
 
diff --git a/go.mod b/go.mod
index 37a67fcdd..fd1c2de81 100644
--- a/go.mod
+++ b/go.mod
@@ -17,7 +17,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200318135427-31631a9ef51f
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200325174927-327088cdef10
 	github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200424101831-2f10e8068538
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200427134702-21db6d1430e3
 	github.com/matrix-org/naffka v0.0.0-20200422140631-181f1ee7401f
 	github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7
 	github.com/mattn/go-sqlite3 v2.0.2+incompatible
diff --git a/go.sum b/go.sum
index 517a77b3d..156f67252 100644
--- a/go.sum
+++ b/go.sum
@@ -367,8 +367,8 @@ github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26 h1:Hr3zjRsq2bh
 github.com/matrix-org/gomatrix v0.0.0-20190528120928-7df988a63f26/go.mod h1:3fxX6gUjWyI/2Bt7J1OLhpCzOfO/bB3AiX0cJtEKud0=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200124100636-0c2ec91d1df5 h1:kmRjpmFOenVpOaV/DRlo9p6z/IbOKlUC+hhKsAAh8Qg=
 github.com/matrix-org/gomatrixserverlib v0.0.0-20200124100636-0c2ec91d1df5/go.mod h1:FsKa2pWE/bpQql9H7U4boOPXFoJX/QcqaZZ6ijLkaZI=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200424101831-2f10e8068538 h1:kj2LdNOdg2+vydS9HrPdbECEVeusRg9VTSOkYm61reA=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200424101831-2f10e8068538/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200427134702-21db6d1430e3 h1:aJMAKjfXG5I8TqPxJQbQIkGSWM770oxkpgsPHE8C06E=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200427134702-21db6d1430e3/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1 h1:osLoFdOy+ChQqVUn2PeTDETFftVkl4w9t/OW18g3lnk=
 github.com/matrix-org/naffka v0.0.0-20200127221512-0716baaabaf1/go.mod h1:cXoYQIENbdWIQHt1SyCo6Bl3C3raHwJ0wgVrXHSqf+A=
 github.com/matrix-org/naffka v0.0.0-20200422140631-181f1ee7401f h1:pRz4VTiRCO4zPlEMc3ESdUOcW4PXHH4Kj+YDz1XyE+Y=
diff --git a/syncapi/routing/messages.go b/syncapi/routing/messages.go
index 873ee9366..53a9a963a 100644
--- a/syncapi/routing/messages.go
+++ b/syncapi/routing/messages.go
@@ -210,7 +210,10 @@ func (r *messagesReq) retrieveEvents() (
 	}
 
 	// Sort the events to ensure we send them in the right order.
-	events = gomatrixserverlib.HeaderedReverseTopologicalOrdering(events)
+	events = gomatrixserverlib.HeaderedReverseTopologicalOrdering(
+		events,
+		gomatrixserverlib.TopologicalOrderByPrevEvents,
+	)
 	if r.backwardOrdering {
 		// This reverses the array from old->new to new->old
 		sort.SliceStable(events, func(i, j int) bool {