2 files changed, 2 insertions, 2 deletions

diff --git a/README.md b/README.md
index 65b9dc2..0e13d9b 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# MathExecutor [![Build Status](https://travis-ci.org/NeonXP/MathExecutor.png?branch=master)](https://travis-ci.org/NeonXP/MathExecutor)
+# MathExecutor [![Build Status](https://travis-ci.org/NeonXP/MathExecutor.png?branch=master)](https://travis-ci.org/NeonXP/MathExecutor) [![Latest Packagist release](https://img.shields.io/packagist/v/nxp/math-executor.svg)](https://packagist.org/packages/nxp/math-executor)
 
 # A simple and extensible math expressions calculator
 
diff --git a/src/NXP/MathExecutor.php b/src/NXP/MathExecutor.php
index 5fdc78f..9a45589 100644
--- a/src/NXP/MathExecutor.php
+++ b/src/NXP/MathExecutor.php
@@ -30,7 +30,7 @@ class MathExecutor
      *
      * @var array
      */
-    public $variables = [];
+    private $variables = [];
 
     /**
      * @var Operator[]