diff --git a/cmd/server/matrix.go b/cmd/server/matrix.go
index ba76c21..82671d8 100644
--- a/cmd/server/matrix.go
+++ b/cmd/server/matrix.go
@@ -1,4 +1,4 @@
-package main
+package main
 
 import (
 	"context"
@@ -9,11 +9,13 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"maunium.net/go/mautrix"
 	"maunium.net/go/mautrix/crypto/cryptohelper"
 	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/id"
 )
 
 type MatrixClient struct {
@@ -24,6 +26,8 @@ type MatrixClient struct {
 	TimeLocation  *time.Location
 	httpClient    *http.Client
 	crypto        *cryptohelper.CryptoHelper
+	cryptoClient  *mautrix.Client
+	syncOnce      sync.Once
 }
 
 func newMatrixClientFromEnv() *MatrixClient {
@@ -59,19 +63,21 @@ func newMatrixClientFromEnv() *MatrixClient {
 	}
 
 	if readEnv("MATRIX_ENABLE_CRYPTO", "1") != "0" {
-		m.crypto = initMatrixCrypto(hs, token)
+		m.crypto, m.cryptoClient = initMatrixCrypto(hs, token)
+		m.startCryptoSync()
 	}
 	return m
 }
 
-func initMatrixCrypto(hs, token string) *cryptohelper.CryptoHelper {
+func initMatrixCrypto(hs, token string) (*cryptohelper.CryptoHelper, *mautrix.Client) {
 	cli, err := mautrix.NewClient(hs, "", token)
 	if err != nil {
-		return nil
+		return nil, nil
 	}
 
 	if whoami, err := cli.Whoami(context.Background()); err == nil && whoami != nil {
 		cli.SetCredentials(whoami.UserID, token)
+		cli.DeviceID = whoami.DeviceID
 	}
 
 	storePath := readEnv("MATRIX_CRYPTO_STORE_PATH", "/tmp/farmcal-matrix-crypto.db")
@@ -79,12 +85,23 @@ func initMatrixCrypto(hs, token string) *cryptohelper.CryptoHelper {
 
 	helper, err := cryptohelper.NewCryptoHelper(cli, pickleKey, storePath)
 	if err != nil {
-		return nil
+		return nil, nil
 	}
 	if err = helper.Init(context.Background()); err != nil {
-		return nil
+		return nil, nil
 	}
-	return helper
+	return helper, cli
+}
+
+func (m *MatrixClient) startCryptoSync() {
+	if m.cryptoClient == nil || m.crypto == nil {
+		return
+	}
+	m.syncOnce.Do(func() {
+		go func() {
+			_ = m.cryptoClient.SyncWithContext(context.Background())
+		}()
+	})
 }
 
 func (m *MatrixClient) FetchRecentMessages(ctx context.Context) ([]MatrixMessage, error) {
@@ -126,6 +143,7 @@ func (m *MatrixClient) FetchRecentMessages(ctx context.Context) ([]MatrixMessage
 		if err := json.Unmarshal(messagesResp.Chunk[i], ev); err != nil {
 			continue
 		}
+		ev.RoomID = id.RoomID(m.RoomID)
 		msg, ok := m.mapEventToMessage(ctx, ev)
 		if ok {
 			out = append(out, msg)
@@ -147,6 +165,15 @@ func (m *MatrixClient) mapEventToMessage(ctx context.Context, ev *event.Event) (
 	case event.EventEncrypted:
 		if m.crypto != nil {
 			decrypted, err := m.crypto.Decrypt(ctx, ev)
+			if errors.Is(err, cryptohelper.NoSessionFound) {
+				content := ev.Content.AsEncrypted()
+				m.crypto.RequestSession(ctx, ev.RoomID, content.SenderKey, content.SessionID, ev.Sender, content.DeviceID)
+				waitCtx, cancel := context.WithTimeout(ctx, 8*time.Second)
+				if m.crypto.WaitForSession(waitCtx, ev.RoomID, content.SenderKey, content.SessionID, 7*time.Second) {
+					decrypted, err = m.crypto.Decrypt(ctx, ev)
+				}
+				cancel()
+			}
 			if err == nil && decrypted != nil {
 				if body, ok := extractBody(decrypted); ok {
 					return MatrixMessage{Sender: sender, Body: body, Timestamp: ts}, true