diff --git a/src/Symfony/Component/HttpKernel/Kernel.php b/src/Symfony/Component/HttpKernel/Kernel.php
index 9e283b47717f9..6d71214f1be70 100644
--- a/src/Symfony/Component/HttpKernel/Kernel.php
+++ b/src/Symfony/Component/HttpKernel/Kernel.php
@@ -597,10 +597,9 @@ protected function initializeContainer()
             return;
         }
 
-        if ($this->debug) {
+        if ($collectDeprecations = $this->debug && !\defined('PHPUNIT_COMPOSER_INSTALL')) {
             $collectedLogs = [];
-            $previousHandler = \defined('PHPUNIT_COMPOSER_INSTALL');
-            $previousHandler = $previousHandler ?: set_error_handler(function ($type, $message, $file, $line) use (&$collectedLogs, &$previousHandler) {
+            $previousHandler = set_error_handler(function ($type, $message, $file, $line) use (&$collectedLogs, &$previousHandler) {
                 if (E_USER_DEPRECATED !== $type && E_DEPRECATED !== $type) {
                     return $previousHandler ? $previousHandler($type, $message, $file, $line) : false;
                 }
@@ -636,7 +635,7 @@ protected function initializeContainer()
             $container = $this->buildContainer();
             $container->compile();
         } finally {
-            if ($this->debug && true !== $previousHandler) {
+            if ($collectDeprecations) {
                 restore_error_handler();
 
                 file_put_contents($cacheDir.'/'.$class.'Deprecations.log', serialize(array_values($collectedLogs)));