diff --git a/src/Medoo.php b/src/Medoo.php
index 2b113fb9..8a5322e7 100644
--- a/src/Medoo.php
+++ b/src/Medoo.php
@@ -2,7 +2,7 @@
 /*!
  * Medoo database framework
  * https://medoo.in
- * Version 1.5.1
+ * Version 1.5.2
  *
  * Copyright 2017, Angel Lai
  * Released under the MIT license
@@ -1032,7 +1032,7 @@ protected function columnMap($columns, &$stack)
 			{
 				preg_match('/([a-zA-Z0-9_]+\.)?(?<column>[a-zA-Z0-9_]+)(?:\s*\((?<alias>[a-zA-Z0-9_]+)\))?(?:\s*\[(?<type>(?:String|Bool|Int|Number|Object|JSON))\])?/i', $value, $key_match);
 
-				$column_key = isset($key_match[ 'alias' ]) ?
+				$column_key = !empty($key_match[ 'alias' ]) ?
 					$key_match[ 'alias' ] :
 					$key_match[ 'column' ];