diff --git a/phpunit.dist.xml b/phpunit.dist.xml
index 25947a7f096..c3466004508 100644
--- a/phpunit.dist.xml
+++ b/phpunit.dist.xml
@@ -1,4 +1,6 @@
 <phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="tests/bootstrap.php"
     colors="true"
     verbose="true"
diff --git a/phpunit.xml b/phpunit.xml
index 80861ca33c5..e429cef4d07 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,4 +1,6 @@
 <phpunit
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="tests/bootstrap.php"
     colors="true"
     verbose="true"