diff --git a/Common/Server/Services/ProjectService.ts b/Common/Server/Services/ProjectService.ts
index 519e3a808d..7e79cc74b4 100755
--- a/Common/Server/Services/ProjectService.ts
+++ b/Common/Server/Services/ProjectService.ts
@@ -423,7 +423,7 @@ export class ProjectService extends DatabaseService<Model> {
 
   private async sendSubscriptionChangeWebhookSlackNotification(
     projectId: ObjectID,
-  ) {
+  ): Promise<void> {
     if (NotificationSlackWebhookOnSubscriptionUpdate) {
       // fetch project again.
       const project: Model | null = await this.findOneById({