diff --git a/src/matrix/room/sending/SendQueue.js b/src/matrix/room/sending/SendQueue.js
index 28408e34..7ba48b15 100644
--- a/src/matrix/room/sending/SendQueue.js
+++ b/src/matrix/room/sending/SendQueue.js
@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-import {SortedArray} from "../../../observable/list/SortedArray.js";
+import {SortedArray} from "../../../observable/list/SortedArray";
 import {ConnectionError} from "../../error.js";
 import {PendingEvent, SendStatus} from "./PendingEvent.js";
 import {makeTxnId, isTxnId} from "../../common.js";
diff --git a/src/observable/index.js b/src/observable/index.js
index 35ecaffc..4d7f18a3 100644
--- a/src/observable/index.js
+++ b/src/observable/index.js
@@ -21,7 +21,7 @@ import {JoinedMap} from "./map/JoinedMap.js";
 import {BaseObservableMap} from "./map/BaseObservableMap.js";
 // re-export "root" (of chain) collections
 export { ObservableArray } from "./list/ObservableArray";
-export { SortedArray } from "./list/SortedArray.js";
+export { SortedArray } from "./list/SortedArray";
 export { MappedList } from "./list/MappedList";
 export { AsyncMappedList } from "./list/AsyncMappedList";
 export { ConcatList } from "./list/ConcatList";
diff --git a/src/observable/list/SortedArray.js b/src/observable/list/SortedArray.ts
similarity index 100%
rename from src/observable/list/SortedArray.js
rename to src/observable/list/SortedArray.ts