diff --git a/lib/payments/directbilling.d.ts b/lib/payments/directbilling.d.ts
index 1539294..4bedd86 100644
--- a/lib/payments/directbilling.d.ts
+++ b/lib/payments/directbilling.d.ts
@@ -20,7 +20,7 @@ export declare class DirectBilling {
     getTransactionsPaginated(serviceId: number, page?: number, pageSize?: number): Promise<PaginatedResponse<PartialDbTransaction>>;
     getTransaction(serviceId: number, transactionId: string): Promise<DbTransaction | undefined>;
     createTransaction(serviceId: number, key: string, request: DbTransactionRequest): Promise<DbGenerationResponse | undefined>;
-    checkNotification(key: string, body: any): DbTransaction | undefined;
+    checkNotification(key: string, body: any): DbNotificationRequest | undefined;
     generateSignature(key: string, request: DbTransactionRequest): string;
     generateSignatureNotification(key: string, request: DbNotificationRequest): string;
 }
diff --git a/lib/payments/sms.js b/lib/payments/sms.js
index fd0ef1b..7867ec1 100644
--- a/lib/payments/sms.js
+++ b/lib/payments/sms.js
@@ -185,7 +185,9 @@ class Sms {
     verifySmsCode(serviceId, code, number) {
         return __awaiter(this, void 0, void 0, function* () {
             const response = (yield this.client.post(`/${serviceId}`, { code, number })).data.data;
-            response.used_at = new Date(response.used_at.replace(' ', 'T'));
+            if (response.used_at) {
+                response.used_at = new Date(response.used_at.replace(' ', 'T'));
+            }
             return response;
         });
     }
diff --git a/package.json b/package.json
index b128f7d..efe9e93 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "simpay-typescript-api",
   "author": "Rafał Więcek",
-  "version": "2.2.0",
+  "version": "2.2.1",
   "description": "SimPay.pl API",
   "main": "lib/index.js",
   "types": "lib/index.d.ts",
diff --git a/src/payments/sms.ts b/src/payments/sms.ts
index 0076bd7..31f3be2 100644
--- a/src/payments/sms.ts
+++ b/src/payments/sms.ts
@@ -209,7 +209,9 @@ export class Sms {
     async verifySmsCode(serviceId: number, code: string, number?: number): Promise<VerificationResponse | undefined> {
         const response = (await this.client.post(`/${serviceId}`, { code, number })).data.data;
 
-        response.used_at = new Date(response.used_at.replace(' ', 'T'));
+        if( response.used_at ) {
+            response.used_at = new Date(response.used_at.replace(' ', 'T'));
+        }
 
         return response;
     }