diff --git a/src/Symfony/Component/Dotenv/Dotenv.php b/src/Symfony/Component/Dotenv/Dotenv.php
index 768d06999a..a8b7bebd9f 100644
--- a/src/Symfony/Component/Dotenv/Dotenv.php
+++ b/src/Symfony/Component/Dotenv/Dotenv.php
@@ -102,7 +102,7 @@ final class Dotenv
     public function populate(array $values, bool $overrideExistingVars = false): void
     {
         $updateLoadedVars = false;
-        $loadedVars = array_flip(explode(',', $_SERVER['SYMFONY_DOTENV_VARS'] ?? $_ENV['SYMFONY_DOTENV_VARS'] ?? '')));
+        $loadedVars = array_flip(explode(',', $_SERVER['SYMFONY_DOTENV_VARS'] ?? $_ENV['SYMFONY_DOTENV_VARS'] ?? ''));
 
         foreach ($values as $name => $value) {
             $notHttpName = 0 !== strpos($name, 'HTTP_');