diff --git a/build/scripts/phar-version.php b/build/scripts/phar-version.php
index 620a735f265..1a91016553e 100755
--- a/build/scripts/phar-version.php
+++ b/build/scripts/phar-version.php
@@ -1,20 +1,21 @@
 #!/usr/bin/env php
 <?php declare(strict_types=1);
 
-if (!isset($argv[1]) || !isset($argv[2])) {
+if (!isset($argv[1], $argv[2])) {
     exit(1);
 }
 
 \file_put_contents(
     __DIR__ . '/../tmp/phar/phpunit/Runner/Version.php',
     \str_replace(
-        'private static $pharVersion;',
-        'private static $pharVersion = "' . $argv[1] . '";',
+        'private static $pharVersion = \'\';',
+        'private static $pharVersion = \'' . $argv[1] . '\';',
         \file_get_contents(__DIR__ . '/../tmp/phar/phpunit/Runner/Version.php')
-    )
+    ),
+    \LOCK_EX
 );
 
-if ($argv[2] == 'release') {
+if ($argv[2] === 'release') {
     print $argv[1];
 } else {
     print $argv[2];