diff --git a/phpunit.xml b/phpunit.xml
index b0bb81d474c..4eb744ce305 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -3,6 +3,7 @@
          xsi:noNamespaceSchemaLocation="phpunit.xsd"
          bootstrap="tests/bootstrap.php"
          cacheDirectory=".phpunit.cache"
+         beStrictAboutOutputDuringTests="true"
          failOnRisky="true"
          failOnWarning="true"
          colors="true">