diff --git a/tasks/config/run.js b/tasks/config/run.js
index 8944cbb12bc1..3d9557158ec8 100644
--- a/tasks/config/run.js
+++ b/tasks/config/run.js
@@ -1,5 +1,6 @@
 import { esTestConfig } from '../../src/test_utils/es';
 import { kibanaTestServerUrlParts } from '../../test/kibana_test_server_url_parts';
+import { resolve } from 'path';
 
 const SECOND = 1000;
 const MINUTE = 60 * SECOND;
@@ -134,7 +135,7 @@ module.exports = function (grunt) {
         '--no-base-path',
         '--optimize.lazyPort=5611',
         '--optimize.lazyPrebuild=true',
-        '--optimize.bundleDir=optimize/testUiServer',
+        '--optimize.bundleDir=' + resolve(__dirname, '../../optimize/testUiServer'),
         ...kbnServerFlags,
       ]
     },
@@ -171,7 +172,7 @@ module.exports = function (grunt) {
         '--server.port=5610',
         '--optimize.lazyPort=5611',
         '--optimize.lazyPrebuild=true',
-        '--optimize.bundleDir=optimize/testdev',
+        '--optimize.bundleDir=' + resolve(__dirname, '../../optimize/testdev'),
         ...kbnServerFlags,
       ]
     },