diff --git a/src/matrix/storage/idb/Transaction.js b/src/matrix/storage/idb/Transaction.js
index 93690017..8b85b795 100644
--- a/src/matrix/storage/idb/Transaction.js
+++ b/src/matrix/storage/idb/Transaction.js
@@ -33,7 +33,7 @@ import {InboundGroupSessionStore} from "./stores/InboundGroupSessionStore";
 import {OutboundGroupSessionStore} from "./stores/OutboundGroupSessionStore";
 import {GroupSessionDecryptionStore} from "./stores/GroupSessionDecryptionStore";
 import {OperationStore} from "./stores/OperationStore";
-import {AccountDataStore} from "./stores/AccountDataStore.js";
+import {AccountDataStore} from "./stores/AccountDataStore";
 
 export class Transaction {
     constructor(txn, allowedStoreNames, IDBKeyRange) {
diff --git a/src/matrix/storage/idb/stores/AccountDataStore.js b/src/matrix/storage/idb/stores/AccountDataStore.ts
similarity index 57%
rename from src/matrix/storage/idb/stores/AccountDataStore.js
rename to src/matrix/storage/idb/stores/AccountDataStore.ts
index 7f22a518..1a7e3e68 100644
--- a/src/matrix/storage/idb/stores/AccountDataStore.js
+++ b/src/matrix/storage/idb/stores/AccountDataStore.ts
@@ -13,17 +13,25 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
+import {Store} from "../Store"
+
+interface AccountDataEntry {
+    type: string
+    content: { [key : string] : any }
+}
 
 export class AccountDataStore {
-	constructor(store) {
-		this._store = store;
-	}
+    private _store: Store<AccountDataEntry>
 
-	async get(type) {
-		return await this._store.get(type);
-	}
+    constructor(store: Store<AccountDataEntry>) {
+        this._store = store;
+    }
 
-	set(event) {
-		return this._store.put(event);
-	}
+    async get(type: string): Promise<AccountDataEntry | null> {
+        return await this._store.get(type);
+    }
+
+    set(event: AccountDataEntry): Promise<IDBValidKey> {
+        return this._store.put(event);
+    }
 }