diff --git a/src/Csv.php b/src/Csv.php
index 70bbbcf..7a8c2f9 100644
--- a/src/Csv.php
+++ b/src/Csv.php
@@ -739,7 +739,8 @@ class Csv {
 
         $this->titles = $head;
         if (!empty($this->sort_by)) {
-            $this->sort_reverse ? krsort($rows, $this->sort_type) : ksort($rows, $this->sort_type);
+            $sort_type = SortEnum::getSorting($this->sort_type);
+            $this->sort_reverse ? krsort($rows, $sort_type) : ksort($rows, $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
index 42626ef..54c3040 100644
--- a/src/enums/SortEnum.php
+++ b/src/enums/SortEnum.php
@@ -5,9 +5,24 @@ namespace ParseCsv\enums;
 class SortEnum extends AbstractEnum {
     const __DEFAULT = self::SORT_TYPE_REGULAR;
 
-    const SORT_TYPE_REGULAR = SORT_REGULAR;
+    const SORT_TYPE_REGULAR = 'regular';
 
-    const SORT_TYPE_NUMERIC = SORT_NUMERIC;
+    const SORT_TYPE_NUMERIC = 'numeric';
+
+    const SORT_TYPE_STRING = 'string';
+
+    private static $sorting = array(
+        self::SORT_TYPE_REGULAR => SORT_REGULAR,
+        self::SORT_TYPE_STRING => SORT_STRING,
+        self::SORT_TYPE_NUMERIC => SORT_NUMERIC
+    );
+
+    public static function getSorting($type){
+        if (array_key_exists($type, self::$sorting)){
+            return self::$sorting[$type];
+        }
+
+        return self::$sorting[self::__DEFAULT];
+    }
 
-    const SORT_TYPE_STRING = SORT_STRING;
 }
diff --git a/tests/properties/PublicPropertiesTest.php b/tests/properties/PublicPropertiesTest.php
index 0510e73..ed49354 100644
--- a/tests/properties/PublicPropertiesTest.php
+++ b/tests/properties/PublicPropertiesTest.php
@@ -152,14 +152,20 @@ class PublicPropertiesTest extends TestCase {
     }
 
     public function testSetSortType(){
-        $this->csv->sort_type = SortEnum::SORT_TYPE_NUMERIC;
+        $this->csv->sort_type = 'numeric';
         $this->assertEquals(SortEnum::SORT_TYPE_NUMERIC,  $this->csv->sort_type);
 
-        $this->csv->sort_type = SortEnum::SORT_TYPE_STRING;
+        $this->csv->sort_type = 'string';
         $this->assertEquals(SortEnum::SORT_TYPE_STRING,  $this->csv->sort_type);
+    }
 
-        $this->csv->sort_type = SortEnum::SORT_TYPE_UNKNOWN;
-        // todo: how to handle this exception?
-        $this->expectException(InvalidArgumentException::class);
+    public function testGetSorting(){
+        $this->csv->sort_type = 'numeric';
+        $sorting = SortEnum::getSorting($this->csv->sort_type);
+        $this->assertEquals(SORT_NUMERIC,  $sorting);
+
+        $this->csv->sort_type = 'string';
+        $sorting = SortEnum::getSorting($this->csv->sort_type);
+        $this->assertEquals(SORT_STRING,  $sorting);
     }
 }