diff --git a/src/Symfony/Bridge/PhpUnit/bootstrap.php b/src/Symfony/Bridge/PhpUnit/bootstrap.php
index f2064368f41a3..daac7b6e3f0a9 100644
--- a/src/Symfony/Bridge/PhpUnit/bootstrap.php
+++ b/src/Symfony/Bridge/PhpUnit/bootstrap.php
@@ -24,6 +24,11 @@
     return;
 }
 
+// Detect if we're under PHPUnit 10 (not compatible yet!)
+if (class_exists(\PHPUnit\Event\Event::class)) {
+    return;
+}
+
 // Enforce a consistent locale
 setlocale(\LC_ALL, 'C');