diff --git a/src/Csv.php b/src/Csv.php
index 74381e4..f75bb0d 100644
--- a/src/Csv.php
+++ b/src/Csv.php
@@ -1,6 +1,7 @@
 <?php
 namespace ParseCsv;
 
+use ParseCsv\enums\SortEnum;
 use ParseCsv\extensions\DatatypeTrait;
 
 class Csv {
@@ -124,7 +125,7 @@ class Csv {
      *
      * @var string|null
      */
-    public $sort_type = null;
+    public $sort_type = SortEnum::SORT_TYPE_REGULAR;
 
     /**
      * Delimiter
@@ -726,14 +727,7 @@ class Csv {
 
         $this->titles = $head;
         if (!empty($this->sort_by)) {
-            $sort_type = SORT_REGULAR;
-            if ($this->sort_type == 'numeric') {
-                $sort_type = SORT_NUMERIC;
-            } elseif ($this->sort_type == 'string') {
-                $sort_type = SORT_STRING;
-            }
-
-            $this->sort_reverse ? krsort($rows, $sort_type) : ksort($rows, $sort_type);
+            $this->sort_reverse ? krsort($rows, $this->sort_type) : ksort($rows, $this->sort_type);
 
             if ($this->offset !== null || $this->limit !== null) {
                 $rows = array_slice($rows, ($this->offset === null ? 0 : $this->offset), $this->limit, true);
diff --git a/src/enums/SortEnum.php b/src/enums/SortEnum.php
new file mode 100644
index 0000000..01a37b0
--- /dev/null
+++ b/src/enums/SortEnum.php
@@ -0,0 +1,18 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: sgorzaly
+ * Date: 22.02.18
+ * Time: 20:24
+ */
+
+namespace ParseCsv\enums;
+
+
+class SortEnum {
+    const SORT_TYPE_REGULAR = SORT_REGULAR;
+
+    const SORT_TYPE_NUMERIC = SORT_NUMERIC;
+
+    const SORT_TYPE_STRING = SORT_STRING;
+}