diff --git a/server/apps/immich/src/config/asset-upload.config.spec.ts b/server/apps/immich/src/config/asset-upload.config.spec.ts
index 89e698ff6c..fbe4d20f91 100644
--- a/server/apps/immich/src/config/asset-upload.config.spec.ts
+++ b/server/apps/immich/src/config/asset-upload.config.spec.ts
@@ -179,5 +179,18 @@ describe('assetUploadOption', () => {
       expect(error).toBeNull();
       expect(name.endsWith(mock.userRequest.body.fileExtension)).toBeTruthy();
     });
+
+    it('should not change the casing of the extension', () => {
+      // Case is deliberately mixed to cover both .upper() and .lower()
+      const body = { ...mock.userRequest.body, fileExtension: '.JpEg' };
+      const request = { ...mock.userRequest, body } as Request;
+
+      filename(request, mock.file, callback);
+
+      expect(callback).toHaveBeenCalled();
+      const [error, name] = callback.mock.calls[0];
+      expect(error).toBeNull();
+      expect(name.endsWith(body.fileExtension)).toBeTruthy();
+    });
   });
 });
diff --git a/server/apps/immich/src/config/asset-upload.config.ts b/server/apps/immich/src/config/asset-upload.config.ts
index d1449c470c..a262b3023e 100644
--- a/server/apps/immich/src/config/asset-upload.config.ts
+++ b/server/apps/immich/src/config/asset-upload.config.ts
@@ -97,6 +97,6 @@ function filename(req: Request, file: Express.Multer.File, cb: any) {
     return cb(null, sanitize(livePhotoFileName));
   }
 
-  const fileName = `${fileNameUUID}${req.body['fileExtension'].toLowerCase()}`;
+  const fileName = `${fileNameUUID}${req.body['fileExtension']}`;
   return cb(null, sanitize(fileName));
 }