diff --git a/app/lib/app.ts b/app/lib/app.ts
index 5dfa8bcb..c6426592 100644
--- a/app/lib/app.ts
+++ b/app/lib/app.ts
@@ -58,7 +58,7 @@ export class Application {
         }
     }
 
-    async send (event: string, ...args): void {
+    async send (event: string, ...args): Promise<void> {
         if (!this.hasWindows()) {
             await this.newWindow()
         }
@@ -97,7 +97,7 @@ export class Application {
         }
     }
 
-    hasWindows (): bool {
+    hasWindows (): boolean {
         return !!this.windows.length
     }
 
diff --git a/app/lib/window.ts b/app/lib/window.ts
index 1aee9bbc..42a8a055 100644
--- a/app/lib/window.ts
+++ b/app/lib/window.ts
@@ -155,7 +155,7 @@ export class Window {
         this.window.webContents.send(event, ...args)
     }
 
-    isDestroyed (): void {
+    isDestroyed (): boolean {
         return !this.window || this.window.isDestroyed()
     }