diff --git a/src/matrix/storage/idb/error.ts b/src/matrix/storage/idb/error.ts
index 0b9de95c..3694b587 100644
--- a/src/matrix/storage/idb/error.ts
+++ b/src/matrix/storage/idb/error.ts
@@ -18,7 +18,10 @@ limitations under the License.
 import { StorageError } from "../common";
 
 export class IDBError extends StorageError {
-    constructor(message, source, cause) {
+    storeName: string
+    databaseName: string
+
+    constructor(message: string, source, cause: DOMException | null) {
         const storeName = source?.name || "<unknown store>";
         const databaseName = source?.transaction?.db?.name || "<unknown db>";
         let fullMessage = `${message} on ${databaseName}.${storeName}`;
@@ -34,14 +37,14 @@ export class IDBError extends StorageError {
         if (cause) {
             fullMessage += cause.message;
         }
-        super(fullMessage, cause);
+        super(fullMessage, cause || undefined);
         this.storeName = storeName;
         this.databaseName = databaseName;
     }
 }
 
 export class IDBRequestError extends IDBError {
-    constructor(request, message = "IDBRequest failed") {
+    constructor(request: IDBRequest, message: string = "IDBRequest failed") {
         const source = request.source;
         const cause = request.error;
         super(message, source, cause);
@@ -49,7 +52,7 @@ export class IDBRequestError extends IDBError {
 }
 
 export class IDBRequestAttemptError extends IDBError {
-    constructor(method, source, cause, params) {
+    constructor(method: string, source, cause: DOMException, params: any[]) {
         super(`${method}(${params.map(p => JSON.stringify(p)).join(", ")}) failed`, source, cause);
     }
 }