diff --git a/app/Helpers/CourseHelper.ts b/app/Helpers/CourseHelper.ts
index 4d13385..369b0e6 100644
--- a/app/Helpers/CourseHelper.ts
+++ b/app/Helpers/CourseHelper.ts
@@ -16,7 +16,7 @@ export default class CourseHelper {
   }
 
   public static getMaterialFileNames(course: Course): FileEntry[] {
-    const data = course.lessons.map(l => l.materials.map(m => ({ path: 'materials/', name: m.name }))).flat();
+    const data = course.lessons.flatMap(l => l.materials.map(m => ({ path: 'materials/', name: m.name })));
     return data;
   }
 
diff --git a/app/Services/CourseService.ts b/app/Services/CourseService.ts
index 1535661..8a569b4 100644
--- a/app/Services/CourseService.ts
+++ b/app/Services/CourseService.ts
@@ -732,11 +732,8 @@ export default class CourseService {
      * Collect file names
      */
     const images = courses.map(course => CourseHelper.getImageFileName(course)).filter(Boolean) as FileEntry[];
-    const videos = courses
-      .map(course => CourseHelper.getVideoFileNames(course))
-      .flat()
-      .filter(Boolean) as FileEntry[];
-    const materials = courses.map(course => CourseHelper.getMaterialFileNames(course)).flat();
+    const videos = courses.flatMap(course => CourseHelper.getVideoFileNames(course)).filter(Boolean) as FileEntry[];
+    const materials = courses.flatMap(course => CourseHelper.getMaterialFileNames(course));
 
     /**
      * Remove files from disk