diff --git a/src/matrix/storage/idb/QueryTarget.ts b/src/matrix/storage/idb/QueryTarget.ts
index 4e8fa7f4..27baf233 100644
--- a/src/matrix/storage/idb/QueryTarget.ts
+++ b/src/matrix/storage/idb/QueryTarget.ts
@@ -15,14 +15,22 @@ limitations under the License.
 */
 
 import {iterateCursor, reqAsPromise} from "./utils";
-import {QueryTargetWrapper} from "./Store.js"
 
 type Reducer<A,B> = (acc: B, val: A) => B
 
-export class QueryTarget<T> {
-    private _target: QueryTargetWrapper
+interface QueryTargetWrapper<T> {
+    openCursor: (range?: IDBKeyRange | null , direction?: IDBCursorDirection) => IDBRequest<IDBCursorWithValue>
+    openKeyCursor: (range: IDBKeyRange, direction: IDBCursorDirection) => IDBRequest<IDBCursor>
+    supports: (method: string) => boolean
+    keyPath: string
+    get: (key: IDBValidKey) => IDBRequest<T>
+    getKey: (key: IDBValidKey) => IDBRequest<IDBValidKey>
+}
 
-    constructor(target: QueryTargetWrapper) {
+export class QueryTarget<T> {
+    private _target: QueryTargetWrapper<T>
+
+    constructor(target: QueryTargetWrapper<T>) {
         this._target = target;
     }
 
@@ -111,7 +119,7 @@ export class QueryTarget<T> {
     async findMaxKey(range: IDBKeyRange): Promise<IDBValidKey | undefined> {
         const cursor = this._target.openKeyCursor(range, "prev");
         let maxKey;
-        await iterateCursor(cursor, (_, key) => {
+        await iterateCursor(cursor, (value, key) => {
             maxKey = key;
             return {done: true};
         });
@@ -126,7 +134,7 @@ export class QueryTarget<T> {
         });
     }
 
-    async iterateKeys(range: IDBKeyRange, callback: (key: IDBValidKey, cur: IDBCursorWithValue) => boolean) {
+    async iterateKeys(range: IDBKeyRange, callback: (key: IDBValidKey, cur: IDBCursor) => boolean) {
         const cursor = this._target.openKeyCursor(range, "next");
         await iterateCursor(cursor, (_, key, cur) => {
             return {done: callback(key, cur)};
diff --git a/src/matrix/storage/idb/utils.ts b/src/matrix/storage/idb/utils.ts
index 722c180d..53f391e8 100644
--- a/src/matrix/storage/idb/utils.ts
+++ b/src/matrix/storage/idb/utils.ts
@@ -124,9 +124,11 @@ export function txnAsPromise(txn): Promise<void> {
     });
 }
 
-type CursorIterator<T> = (value: T, key: IDBValidKey, cursor: IDBCursorWithValue) => { done: boolean, jumpTo?: IDBValidKey }
+type CursorIterator<T, I extends IDBCursor> = I extends IDBCursorWithValue ?
+    (value: T, key: IDBValidKey, cursor: IDBCursorWithValue) => { done: boolean, jumpTo?: IDBValidKey } :
+    (value: undefined, key: IDBValidKey, cursor: IDBCursor) => { done: boolean, jumpTo?: IDBValidKey }
 
-export function iterateCursor<T>(cursorRequest: IDBRequest<IDBCursorWithValue>, processValue: CursorIterator<T>): Promise<boolean> {
+export function iterateCursor<T, I extends IDBCursor = IDBCursorWithValue>(cursorRequest: IDBRequest<I>, processValue: CursorIterator<T, I>): Promise<boolean> {
     // TODO: does cursor already have a value here??
     return new Promise<boolean>((resolve, reject) => {
         cursorRequest.onerror = () => {
@@ -136,14 +138,14 @@ export function iterateCursor<T>(cursorRequest: IDBRequest<IDBCursorWithValue>,
         };
         // collect results
         cursorRequest.onsuccess = (event) => {
-            const cursor = (event.target as IDBRequest<IDBCursorWithValue>).result;
+            const cursor = (event.target as IDBRequest<I>).result;
             if (!cursor) {
                 resolve(false);
                 // @ts-ignore
                 needsSyncPromise && Promise._flush && Promise._flush();
                 return; // end of results
             }
-            const result = processValue(cursor.value, cursor.key, cursor);
+            const result = processValue(cursor["value"], cursor.key, cursor);
             // TODO: don't use object for result and assume it's jumpTo when not === true/false or undefined
             const done = result?.done;
             const jumpTo = result?.jumpTo;