diff --git a/federationsender/internal/perform.go b/federationsender/internal/perform.go
index e8bb39537..504845f70 100644
--- a/federationsender/internal/perform.go
+++ b/federationsender/internal/perform.go
@@ -192,13 +192,25 @@ func (r *FederationSenderInternalAPI) performJoinUsingServer(
 		return fmt.Errorf("joinCtx.CheckSendJoinResponse: %w", err)
 	}
 
+	// Work out which events were not returned from checking the
+	// send_join response. We'll include these in a map so that we
+	// don't generate input events for them.
+	var invalidEventIDs map[string]bool
+	if invalid := respState.InvalidEventIDs(); len(invalid) > 0 {
+		invalidEventIDs = make(map[string]bool)
+		for _, eventID := range invalid {
+			invalidEventIDs[eventID] = true
+		}
+	}
+
 	// If we successfully performed a send_join above then the other
 	// server now thinks we're a part of the room. Send the newly
 	// returned state to the roomserver to update our local view.
 	if err = roomserverAPI.SendEventWithState(
 		ctx, r.rsAPI,
 		respState,
-		event.Headered(respMakeJoin.RoomVersion), nil,
+		event.Headered(respMakeJoin.RoomVersion),
+		invalidEventIDs,
 	); err != nil {
 		return fmt.Errorf("r.producer.SendEventWithState: %w", err)
 	}
diff --git a/go.mod b/go.mod
index b407c4d80..d25fdf4f0 100644
--- a/go.mod
+++ b/go.mod
@@ -21,7 +21,7 @@ require (
 	github.com/matrix-org/go-http-js-libp2p v0.0.0-20200518170932-783164aeeda4
 	github.com/matrix-org/go-sqlite3-js v0.0.0-20200522092705-bc8506ccbcf3
 	github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd
-	github.com/matrix-org/gomatrixserverlib v0.0.0-20200907140345-a4851252e384
+	github.com/matrix-org/gomatrixserverlib v0.0.0-20200907143659-4b5669b82c8d
 	github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91
 	github.com/matrix-org/util v0.0.0-20200807132607-55161520e1d4
 	github.com/mattn/go-sqlite3 v1.14.2
diff --git a/go.sum b/go.sum
index a538a2912..fa51f058a 100644
--- a/go.sum
+++ b/go.sum
@@ -567,8 +567,8 @@ 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/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd h1:xVrqJK3xHREMNjwjljkAUaadalWc0rRbmVuQatzmgwg=
 github.com/matrix-org/gomatrix v0.0.0-20200827122206-7dd5e2a05bcd/go.mod h1:/gBX06Kw0exX1HrwmoBibFA98yBk/jxKpGVeyQbff+s=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200907140345-a4851252e384 h1:ShZMM8Yh3mWtMUc7MubTrFM+3K/RYg36uXP7LnocxoM=
-github.com/matrix-org/gomatrixserverlib v0.0.0-20200907140345-a4851252e384/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200907143659-4b5669b82c8d h1:nHCJnv2QxP1eQzVhIl9Iwkc5wGaWTzOhcT7wfSpmRl8=
+github.com/matrix-org/gomatrixserverlib v0.0.0-20200907143659-4b5669b82c8d/go.mod h1:JsAzE1Ll3+gDWS9JSUHPJiiyAksvOOnGWF2nXdg4ZzU=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91 h1:HJ6U3S3ljJqNffYMcIeAncp5qT/i+ZMiJ2JC2F0aXP4=
 github.com/matrix-org/naffka v0.0.0-20200901083833-bcdd62999a91/go.mod h1:sjyPyRxKM5uw1nD2cJ6O2OxI6GOqyVBfNXqKjBZTBZE=
 github.com/matrix-org/util v0.0.0-20190711121626-527ce5ddefc7 h1:ntrLa/8xVzeSs8vHFHK25k0C+NV74sYMJnNSg5NoSRo=