diff --git a/bin/composer b/bin/composer
index 823f87a4b442..88566e17014e 100755
--- a/bin/composer
+++ b/bin/composer
@@ -48,6 +48,8 @@ if (function_exists('ini_set')) {
     unset($memoryInBytes, $memoryLimit);
 }
 
+putenv('COMPOSER_BINARY='.realpath($_SERVER['argv'][0]));
+
 // run the command application
 $application = new Application();
 $application->run(null, $output);
diff --git a/src/Composer/EventDispatcher/EventDispatcher.php b/src/Composer/EventDispatcher/EventDispatcher.php
index e6cc378a09b5..fdb00866801e 100644
--- a/src/Composer/EventDispatcher/EventDispatcher.php
+++ b/src/Composer/EventDispatcher/EventDispatcher.php
@@ -180,7 +180,7 @@ protected function doDispatch(Event $event)
                     if (!$phpPath) {
                         throw new \RuntimeException('Failed to locate PHP binary to execute '.$scriptName);
                     }
-                    $exec = $phpPath . '  ' . realpath($_SERVER['argv'][0]) . substr($callable, 9);
+                    $exec = ProcessExecutor::escape($phpPath) . ' ' . ProcessExecutor::escape(getenv('COMPOSER_BINARY')) . substr($callable, 9);
                     if (0 !== ($exitCode = $this->process->execute($exec))) {
                         $this->io->writeError(sprintf('<error>Script %s handling the %s event returned with error code '.$exitCode.'</error>', $callable, $event->getName()));