diff --git a/tests/selenium/wdio.conf.js b/tests/selenium/wdio.conf.js
index f2d4170..5ffad02 100644
--- a/tests/selenium/wdio.conf.js
+++ b/tests/selenium/wdio.conf.js
@@ -9,4 +9,5 @@ exports.config = {
   //
   // Example:
   // logLevel: 'info',
+  maxInstances: 4,
 };