diff --git a/lib/src/room.dart b/lib/src/room.dart
index 59fe39bc..8d5c0022 100644
--- a/lib/src/room.dart
+++ b/lib/src/room.dart
@@ -372,7 +372,7 @@ class Room {
     this.membership = Membership.join,
     int notificationCount,
     int highlightCount,
-    String prev_batch,
+    this.prev_batch,
     this.client,
     this.notificationSettings,
     Map<String, BasicRoomEvent> roomAccountData,
@@ -383,7 +383,6 @@ class Room {
         _oldestSortOrder = oldestSortOrder,
         notificationCount = notificationCount ?? 0,
         highlightCount = highlightCount ?? 0,
-        prev_batch = prev_batch ?? '',
         roomAccountData = roomAccountData ?? <String, BasicRoomEvent>{},
         summary = summary ??
             RoomSummary.fromJson({
@@ -945,6 +944,9 @@ class Room {
   /// the historical events will be published in the onEvent stream.
   Future<void> requestHistory(
       {int historyCount = defaultHistoryCount, onHistoryReceived}) async {
+    if (prev_batch == null) {
+      throw 'Tried to request history without a prev_batch token';
+    }
     final resp = await client.getRoomEvents(
       id,
       prev_batch,
@@ -1105,7 +1107,6 @@ class Room {
       onInsert: onInsert,
     );
     if (client.database == null) {
-      prev_batch = '';
       await requestHistory(historyCount: 10);
     }
     return timeline;
diff --git a/lib/src/utils/room_update.dart b/lib/src/utils/room_update.dart
index 6a8db981..9ea86de0 100644
--- a/lib/src/utils/room_update.dart
+++ b/lib/src/utils/room_update.dart
@@ -66,7 +66,7 @@ class RoomUpdate {
                   update.unreadNotifications?.notificationCount ?? 0,
               highlight_count: update.unreadNotifications?.highlightCount ?? 0,
               limitedTimeline: update.timeline?.limited ?? false,
-              prev_batch: update.timeline?.prevBatch ?? '',
+              prev_batch: update.timeline?.prevBatch,
               summary: update.summary,
             )
           : update is InvitedRoomUpdate
@@ -76,7 +76,7 @@ class RoomUpdate {
                   notification_count: 0,
                   highlight_count: 0,
                   limitedTimeline: false,
-                  prev_batch: '',
+                  prev_batch: null,
                   summary: null,
                 )
               : update is LeftRoomUpdate
@@ -86,7 +86,7 @@ class RoomUpdate {
                       notification_count: 0,
                       highlight_count: 0,
                       limitedTimeline: update.timeline?.limited ?? false,
-                      prev_batch: update.timeline?.prevBatch ?? '',
+                      prev_batch: update.timeline?.prevBatch,
                       summary: null,
                     )
                   : null;
diff --git a/test/client_test.dart b/test/client_test.dart
index 52d9584b..84c70cdd 100644
--- a/test/client_test.dart
+++ b/test/client_test.dart
@@ -233,7 +233,7 @@ void main() {
 
       expect(roomUpdateList[1].id == '!696r7674:example.com', true);
       expect(roomUpdateList[1].membership == Membership.invite, true);
-      expect(roomUpdateList[1].prev_batch == '', true);
+      expect(roomUpdateList[1].prev_batch == null, true);
       expect(roomUpdateList[1].limitedTimeline == false, true);
       expect(roomUpdateList[1].notification_count == 0, true);
       expect(roomUpdateList[1].highlight_count == 0, true);