diff --git a/src/Composer/Util/Tar.php b/src/Composer/Util/Tar.php
index bb8c8c3d2..1fb608f65 100644
--- a/src/Composer/Util/Tar.php
+++ b/src/Composer/Util/Tar.php
@@ -50,7 +50,7 @@ class Tar
         }
 
         $composerJsonPath = key($topLevelPaths).'/composer.json';
-        if ($topLevelPaths && isset($phar[$composerJsonPath])) {
+        if (\count($topLevelPaths) > 0 && isset($phar[$composerJsonPath])) {
             return $phar[$composerJsonPath]->getContent();
         }