diff --git a/src/content/components/file-selector-panel.ts b/src/content/components/file-selector-panel.ts
index d596437..eadc34c 100644
--- a/src/content/components/file-selector-panel.ts
+++ b/src/content/components/file-selector-panel.ts
@@ -405,7 +405,7 @@ export class FileSelectorPanel extends LitElement {
   private getFileType(ext: string): FileType {
     const lowerExt = ext.toLowerCase();
 
-    const videoExts = ['.mp4', '.avi', '.mkv', '.mov', '.wmv', '.flv', '.webm', '.m4v'];
+    const videoExts = ['.mp4', '.avi', '.mkv', '.mov', '.wmv', '.flv', '.webm', '.m4v', '.sup'];
     const imageExts = ['.jpg', '.jpeg', '.png', '.gif', '.bmp', '.svg', '.webp', '.ico'];
     const audioExts = ['.mp3', '.wav', '.flac', '.aac', '.m4a', '.ogg', '.opus', '.wma'];
     const docExts = ['.pdf', '.doc', '.docx', '.xls', '.xlsx', '.ppt', '.pptx', '.txt', '.md'];
diff --git a/tests/unit/file-selector-panel-file-type.test.ts b/tests/unit/file-selector-panel-file-type.test.ts
new file mode 100644
index 0000000..add08e7
--- /dev/null
+++ b/tests/unit/file-selector-panel-file-type.test.ts
@@ -0,0 +1,16 @@
+import { describe, expect, it } from 'vitest';
+import { FileSelectorPanel } from '../../src/content/components/file-selector-panel';
+import type { FileType } from '../../src/types/file-selector';
+
+type FileSelectorPanelTypeHarness = FileSelectorPanel & {
+  getFileType(ext: string): FileType;
+};
+
+describe('FileSelectorPanel file type classification', () => {
+  it('classifies .sup subtitle files with the video filter', () => {
+    const panel = new FileSelectorPanel() as unknown as FileSelectorPanelTypeHarness;
+
+    expect(panel.getFileType('.sup')).toBe('video');
+    expect(panel.getFileType('.SUP')).toBe('video');
+  });
+});