diff --git a/composer.json b/composer.json
index bf1078c..c9a5dd2 100644
--- a/composer.json
+++ b/composer.json
@@ -30,7 +30,7 @@
 	"require": {
 		"php": ">=5.6",
 		"brain/monkey": "^2.7.0",
-		"yoast/phpunit-polyfills": "^1.1.5"
+		"yoast/phpunit-polyfills": "^4.0.0"
 	},
 	"require-dev": {
 		"php-parallel-lint/php-console-highlighter": "^1.0.0",