diff --git a/src/Valitron/Validator.php b/src/Valitron/Validator.php
index d92e2e6..cfb2da1 100644
--- a/src/Valitron/Validator.php
+++ b/src/Valitron/Validator.php
@@ -49,7 +49,8 @@ class Validator
         // Load language file in directory
         $langFile = rtrim($langDir, '/') . '/' . $lang . '.php';
         if ( stream_resolve_include_path($langFile) ) {
-            static::$_ruleMessages = include $langFile;            
+            $langMessages = include $langFile;
+            static::$_ruleMessages = array_merge(static::$_ruleMessages, $langMessages);
         } else {
             throw new InvalidArgumentException("fail to load language file '$langFile'");
         }
diff --git a/tests/Valitron/BaseTestCase.php b/tests/Valitron/BaseTestCase.php
index 0dec6c4..9754f01 100644
--- a/tests/Valitron/BaseTestCase.php
+++ b/tests/Valitron/BaseTestCase.php
@@ -11,6 +11,7 @@ class BaseTestCase extends \PHPUnit_Framework_TestCase
 	{
 		$this->resetProperty('_lang');
 		$this->resetProperty('_langDir');
+		$this->resetProperty('_rules', array());
 		$this->resetProperty('_ruleMessages', array());
 	}
 
diff --git a/tests/Valitron/StaticVsInstanceTest.php b/tests/Valitron/StaticVsInstanceTest.php
index c83dad4..1601189 100644
--- a/tests/Valitron/StaticVsInstanceTest.php
+++ b/tests/Valitron/StaticVsInstanceTest.php
@@ -10,4 +10,21 @@ class StaticVsInstanceTest extends BaseTestCase
 		$this->assertEquals('ar', Validator::lang(),
 							'instance defined lang should not replace static global lang');
 	}
+
+	/**
+	 * Fix bug where rules messages added with Validator::addRule were replaced after creating validator instance
+	 */
+	public function testRuleMessagesReplacedAfterConstructor()
+	{
+		$customMessage = 'custom message';
+		$ruleName = 'customRule';
+		$fieldName = 'fieldName';
+		Validator::addRule($ruleName, function() {}, $customMessage);
+		$v = new Validator(array($fieldName => $fieldName));
+		$v->rule($ruleName, $fieldName);
+		$v->validate();
+		$messages = $v->errors();
+		$this->assertArrayHasKey($fieldName, $messages);
+		$this->assertEquals(ucfirst("$fieldName $customMessage"), $messages[$fieldName][0]);
+	}
 }