diff -u b/core/modules/simpletest/simpletest.module b/core/modules/simpletest/simpletest.module
--- b/core/modules/simpletest/simpletest.module
+++ b/core/modules/simpletest/simpletest.module
@@ -385,7 +385,7 @@
     // On Windows it is necessary to run the script using the PHP executable.
     $php_executable_finder = new PhpExecutableFinder();
     $php = $php_executable_finder->find();
-    $command = escapeshellarg($php) . ' -f ' . escapeshellarg($command) . ' --';
+    $command = $php . ' -f ' . escapeshellarg($command) . ' --';
   }
   return $command;
 }