diff --git a/src/Symfony/Component/VarDumper/VarDumper.php b/src/Symfony/Component/VarDumper/VarDumper.php
index 470a24fe8d211..b223e065106d2 100644
--- a/src/Symfony/Component/VarDumper/VarDumper.php
+++ b/src/Symfony/Component/VarDumper/VarDumper.php
@@ -71,7 +71,7 @@ private static function register(): void
                 $dumper = new CliDumper();
                 break;
             case 'server' === $format:
-            case 'tcp' === parse_url($format, \PHP_URL_SCHEME):
+            case $format && 'tcp' === parse_url($format, \PHP_URL_SCHEME):
                 $host = 'server' === $format ? $_SERVER['VAR_DUMPER_SERVER'] ?? '127.0.0.1:9912' : $format;
                 $dumper = \in_array(\PHP_SAPI, ['cli', 'phpdbg'], true) ? new CliDumper() : new HtmlDumper();
                 $dumper = new ServerDumper($host, $dumper, self::getDefaultContextProviders());