diff --git a/composer.json b/composer.json
index c753be2ab0..804dfb090c 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,8 @@
 		"squizlabs/php_codesniffer": "3.6.0",
 		"wp-coding-standards/wpcs": "~2.3.0",
 		"phpcompatibility/phpcompatibility-wp": "~2.1.2",
-		"phpunit/phpunit": "^5.7 || ^6.5 || ^7.5"
+		"phpunit/phpunit": "^5.7 || ^6.5 || ^7.5",
+		"yoast/phpunit-polyfills": "^1.0"
 	},
 	"scripts": {
 		"compat": "@php ./vendor/squizlabs/php_codesniffer/bin/phpcs --standard=phpcompat.xml.dist --report=summary,source",