diff --git a/src/matrix/storage/idb/StorageFactory.js b/src/matrix/storage/idb/StorageFactory.js
index e91c77ca..259c8c0f 100644
--- a/src/matrix/storage/idb/StorageFactory.js
+++ b/src/matrix/storage/idb/StorageFactory.js
@@ -18,7 +18,7 @@ import {Storage} from "./Storage";
 import { openDatabase, reqAsPromise } from "./utils";
 import { exportSession, importSession } from "./export.js";
 import { schema } from "./schema";
-import { detectWebkitEarlyCloseTxnBug } from "./quirks.js";
+import { detectWebkitEarlyCloseTxnBug } from "./quirks";
 
 const sessionName = sessionId => `hydrogen_session_${sessionId}`;
 const openDatabaseWithSessionId = function(sessionId, idbFactory) {
diff --git a/src/matrix/storage/idb/quirks.js b/src/matrix/storage/idb/quirks.ts
similarity index 94%
rename from src/matrix/storage/idb/quirks.js
rename to src/matrix/storage/idb/quirks.ts
index 5eaa6836..e739da84 100644
--- a/src/matrix/storage/idb/quirks.js
+++ b/src/matrix/storage/idb/quirks.ts
@@ -18,7 +18,7 @@ limitations under the License.
 import {openDatabase, txnAsPromise, reqAsPromise} from "./utils";
 
 // filed as https://bugs.webkit.org/show_bug.cgi?id=222746
-export async function detectWebkitEarlyCloseTxnBug(idbFactory) {
+export async function detectWebkitEarlyCloseTxnBug(idbFactory: IDBFactory): Promise<boolean> {
     const dbName = "hydrogen_webkit_test_inactive_txn_bug";
     try {
         const db = await openDatabase(dbName, db => {