diff --git a/database/backfillqueue.go b/database/backfill.go
similarity index 70%
rename from database/backfillqueue.go
rename to database/backfill.go
index 6738877..1a0979b 100644
--- a/database/backfillqueue.go
+++ b/database/backfill.go
@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	log "maunium.net/go/maulogger/v2"
@@ -51,6 +52,8 @@ func (bt BackfillType) String() string {
 type BackfillQuery struct {
 	db  *Database
 	log log.Logger
+
+	backfillQueryLock sync.Mutex
 }
 
 func (bq *BackfillQuery) New() *Backfill {
@@ -96,6 +99,9 @@ const (
 
 // GetNext returns the next backfill to perform
 func (bq *BackfillQuery) GetNext(userID id.UserID, backfillTypes []BackfillType) (backfill *Backfill) {
+	bq.backfillQueryLock.Lock()
+	defer bq.backfillQueryLock.Unlock()
+
 	types := []string{}
 	for _, backfillType := range backfillTypes {
 		types = append(types, strconv.Itoa(int(backfillType)))
@@ -113,6 +119,8 @@ func (bq *BackfillQuery) GetNext(userID id.UserID, backfillTypes []BackfillType)
 }
 
 func (bq *BackfillQuery) DeleteAll(userID id.UserID) {
+	bq.backfillQueryLock.Lock()
+	defer bq.backfillQueryLock.Unlock()
 	_, err := bq.db.Exec("DELETE FROM backfill_queue WHERE user_mxid=$1", userID)
 	if err != nil {
 		bq.log.Warnfln("Failed to delete backfill queue items for %s: %v", userID, err)
@@ -120,6 +128,8 @@ func (bq *BackfillQuery) DeleteAll(userID id.UserID) {
 }
 
 func (bq *BackfillQuery) DeleteAllForPortal(userID id.UserID, portalKey PortalKey) {
+	bq.backfillQueryLock.Lock()
+	defer bq.backfillQueryLock.Unlock()
 	_, err := bq.db.Exec(`
 		DELETE FROM backfill_queue
 		WHERE user_mxid=$1
@@ -167,6 +177,9 @@ func (b *Backfill) Scan(row Scannable) *Backfill {
 }
 
 func (b *Backfill) Insert() {
+	b.db.Backfill.backfillQueryLock.Lock()
+	defer b.db.Backfill.backfillQueryLock.Unlock()
+
 	rows, err := b.db.Query(`
 		INSERT INTO backfill_queue
 			(user_mxid, type, priority, portal_jid, portal_receiver, time_start, max_batch_events, max_total_events, batch_delay, dispatch_time, completed_at)
@@ -185,6 +198,9 @@ func (b *Backfill) Insert() {
 }
 
 func (b *Backfill) MarkDispatched() {
+	b.db.Backfill.backfillQueryLock.Lock()
+	defer b.db.Backfill.backfillQueryLock.Unlock()
+
 	if b.QueueID == 0 {
 		b.log.Errorf("Cannot mark backfill as dispatched without queue_id. Maybe it wasn't actually inserted in the database?")
 		return
@@ -196,6 +212,9 @@ func (b *Backfill) MarkDispatched() {
 }
 
 func (b *Backfill) MarkDone() {
+	b.db.Backfill.backfillQueryLock.Lock()
+	defer b.db.Backfill.backfillQueryLock.Unlock()
+
 	if b.QueueID == 0 {
 		b.log.Errorf("Cannot mark backfill done without queue_id. Maybe it wasn't actually inserted in the database?")
 		return
@@ -205,3 +224,79 @@ func (b *Backfill) MarkDone() {
 		b.log.Warnfln("Failed to mark %s/%s as complete: %v", b.BackfillType, b.Priority, err)
 	}
 }
+
+func (bq *BackfillQuery) NewBackfillState(userID id.UserID, portalKey *PortalKey) *BackfillState {
+	return &BackfillState{
+		db:     bq.db,
+		log:    bq.log,
+		UserID: userID,
+		Portal: portalKey,
+	}
+}
+
+const (
+	getBackfillState = `
+		SELECT user_mxid, portal_jid, portal_receiver, processing_batch, backfill_complete, first_expected_ts
+		FROM backfill_state
+		WHERE user_mxid=$1
+			AND portal_jid=$2
+			AND portal_receiver=$3
+	`
+)
+
+type BackfillState struct {
+	db  *Database
+	log log.Logger
+
+	// Fields
+	UserID                 id.UserID
+	Portal                 *PortalKey
+	ProcessingBatch        bool
+	BackfillComplete       bool
+	FirstExpectedTimestamp uint64
+}
+
+func (b *BackfillState) Scan(row Scannable) *BackfillState {
+	err := row.Scan(&b.UserID, &b.Portal.JID, &b.Portal.Receiver, &b.ProcessingBatch, &b.BackfillComplete, &b.FirstExpectedTimestamp)
+	if err != nil {
+		if !errors.Is(err, sql.ErrNoRows) {
+			b.log.Errorln("Database scan failed:", err)
+		}
+		return nil
+	}
+	return b
+}
+
+func (b *BackfillState) Upsert() {
+	_, err := b.db.Exec(`
+		INSERT INTO backfill_state
+			(user_mxid, portal_jid, portal_receiver, processing_batch, backfill_complete, first_expected_ts)
+		VALUES ($1, $2, $3, $4, $5, $6)
+		ON CONFLICT (user_mxid, portal_jid, portal_receiver)
+		DO UPDATE SET
+			processing_batch=EXCLUDED.processing_batch,
+			backfill_complete=EXCLUDED.backfill_complete,
+			first_expected_ts=EXCLUDED.first_expected_ts`,
+		b.UserID, b.Portal.JID, b.Portal.Receiver, b.ProcessingBatch, b.BackfillComplete, b.FirstExpectedTimestamp)
+	if err != nil {
+		b.log.Warnfln("Failed to insert backfill state for %s: %v", b.Portal.JID, err)
+	}
+}
+
+func (b *BackfillState) SetProcessingBatch(processing bool) {
+	b.ProcessingBatch = processing
+	b.Upsert()
+}
+
+func (bq *BackfillQuery) GetBackfillState(userID id.UserID, portalKey *PortalKey) (backfillState *BackfillState) {
+	rows, err := bq.db.Query(getBackfillState, userID, portalKey.JID, portalKey.Receiver)
+	if err != nil || rows == nil {
+		bq.log.Error(err)
+		return
+	}
+	defer rows.Close()
+	if rows.Next() {
+		backfillState = bq.NewBackfillState(userID, portalKey).Scan(rows)
+	}
+	return
+}
diff --git a/database/upgrades/2022-05-16-room-backfill-state.go b/database/upgrades/2022-05-16-room-backfill-state.go
index f7de55f..976b129 100644
--- a/database/upgrades/2022-05-16-room-backfill-state.go
+++ b/database/upgrades/2022-05-16-room-backfill-state.go
@@ -13,7 +13,7 @@ func init() {
 				portal_receiver     TEXT,
 				processing_batch    BOOLEAN,
 				backfill_complete   BOOLEAN,
-				first_expected_ts   TIMESTAMP,
+				first_expected_ts   INTEGER,
 
 				PRIMARY KEY (user_mxid, portal_jid, portal_receiver),
 				FOREIGN KEY (user_mxid) REFERENCES "user"(mxid) ON DELETE CASCADE ON UPDATE CASCADE,
diff --git a/historysync.go b/historysync.go
index 5c2e6ca..00f0e2a 100644
--- a/historysync.go
+++ b/historysync.go
@@ -130,6 +130,13 @@ func (user *User) backfillInChunks(req *database.Backfill, conv *database.Histor
 	portal.backfillLock.Lock()
 	defer portal.backfillLock.Unlock()
 
+	backfillState := user.bridge.DB.Backfill.GetBackfillState(user.MXID, &portal.Key)
+	if backfillState == nil {
+		backfillState = user.bridge.DB.Backfill.NewBackfillState(user.MXID, &portal.Key)
+	}
+	backfillState.SetProcessingBatch(true)
+	defer backfillState.SetProcessingBatch(false)
+
 	if !user.shouldCreatePortalForHistorySync(conv, portal) {
 		return
 	}
@@ -241,6 +248,26 @@ func (user *User) backfillInChunks(req *database.Backfill, conv *database.Histor
 		user.log.Warnfln("Failed to delete %d history sync messages after backfilling (queue ID: %d): %v", len(allMsgs), req.QueueID, err)
 	}
 
+	if req.TimeStart == nil {
+		// If the time start is nil, then there's no more history to backfill.
+		backfillState.BackfillComplete = true
+
+		if conv.EndOfHistoryTransferType == waProto.Conversation_COMPLETE_BUT_MORE_MESSAGES_REMAIN_ON_PRIMARY {
+			// Since there are more messages on the phone, but we can't
+			// backfilll any more of them, indicate that the last timestamp
+			// that we expect to be backfilled is the oldest one that was just
+			// backfilled.
+			backfillState.FirstExpectedTimestamp = allMsgs[len(allMsgs)-1].GetMessageTimestamp()
+		} else if conv.EndOfHistoryTransferType == waProto.Conversation_COMPLETE_AND_NO_MORE_MESSAGE_REMAIN_ON_PRIMARY {
+			// Since there are no more messages left on the phone, we've
+			// backfilled everything. Indicate so by setting the expected
+			// timestamp to 0 which means that the backfill goes to the
+			// beginning of time.
+			backfillState.FirstExpectedTimestamp = 0
+		}
+		backfillState.Upsert()
+	}
+
 	if !conv.MarkedAsUnread && conv.UnreadCount == 0 {
 		user.markSelfReadFull(portal)
 	} else if user.bridge.Config.Bridge.SyncManualMarkedUnread {