diff --git a/src/Valitron/Validator.php b/src/Valitron/Validator.php
index cb7cc8e..e25de20 100644
--- a/src/Valitron/Validator.php
+++ b/src/Valitron/Validator.php
@@ -1,6 +1,8 @@
 <?php
 namespace Valitron;
 
+use InvalidArgumentException;
+
 /**
  * Validation Class
  *
@@ -44,8 +46,13 @@ class Validator
         // set langDir in the follow order: constructor param, static::$_langDir, default to package lang dir
         $langDir = $langDir ?: static::langDir();
 
-        static::langDir($langDir);
-        static::lang($lang);
+        // Load language file in directory
+        $langFile = rtrim($langDir, '/') . '/' . $lang . '.php';
+        if ( stream_resolve_include_path($langFile) ) {
+            static::$_ruleMessages = include $langFile;            
+        } else {
+            throw new InvalidArgumentException("fail to load language file '$langFile'");
+        }
     }
 
     /**
@@ -55,10 +62,6 @@ class Validator
     {
         if($lang !== null) {
             static::$_lang = $lang;
-
-            // Load language file in directory
-            $langDir = static::langDir();
-            static::$_ruleMessages = require rtrim($langDir, '/') . '/' . $lang . '.php';
         }
         return static::$_lang ?: 'en';
     }
diff --git a/tests/Valitron/StaticLangTest.php b/tests/Valitron/LangTest.php
similarity index 77%
rename from tests/Valitron/StaticLangTest.php
rename to tests/Valitron/LangTest.php
index 0ff847a..7660dba 100644
--- a/tests/Valitron/StaticLangTest.php
+++ b/tests/Valitron/LangTest.php
@@ -1,7 +1,7 @@
 <?php
 use Valitron\Validator;
 
-class StaticLangTest extends BaseTestCase
+class LangTest extends BaseTestCase
 {
 	protected function getLangDir()
 	{
@@ -41,4 +41,13 @@ class StaticLangTest extends BaseTestCase
 		$validator = new Validator(array());
 		$this->assertEquals(realpath($this->getLangDir()), realpath(Validator::langDir()));
 	}
+
+	/**
+     * @expectedException InvalidArgumentException
+     * @expectedExceptionMessage fail to load language file '/this/dir/does/not/exists/en.php'
+     */
+	public function testLangException()
+	{
+		new Validator(array(), array(), 'en', '/this/dir/does/not/exists');
+	}
 }
diff --git a/tests/Valitron/StaticVsInstanceTest.php b/tests/Valitron/StaticVsInstanceTest.php
new file mode 100644
index 0000000..c83dad4
--- /dev/null
+++ b/tests/Valitron/StaticVsInstanceTest.php
@@ -0,0 +1,13 @@
+<?php
+use Valitron\Validator;
+
+class StaticVsInstanceTest extends BaseTestCase
+{
+	public function testInstanceOverrideStaticLang()
+	{
+		Validator::lang('ar');
+		new Validator(array(), array(), 'en');
+		$this->assertEquals('ar', Validator::lang(),
+							'instance defined lang should not replace static global lang');
+	}
+}