diff --git a/test/evaluation.spec.js b/test/evaluation.spec.js
index 43cc0bb427..fecd6842f4 100644
--- a/test/evaluation.spec.js
+++ b/test/evaluation.spec.js
@@ -263,8 +263,7 @@ module.exports.describe = function({testRunner, expect, FFOX, CHROMIUM, WEBKIT,
       });
       expect(result).toEqual([42]);
     });
-    // Works in WebKit, but slow
-    it.fail(FFOX)('should transfer 100Mb of data from page to node.js', async({page, server}) => {
+    it.slow()('should transfer 100Mb of data from page to node.js', async({page, server}) => {
       const a = await page.evaluate(() => Array(100 * 1024 * 1024 + 1).join('a'));
       expect(a.length).toBe(100 * 1024 * 1024);
     });