diff --git a/src/Datium.php b/src/Datium.php
index 6090713..84a9f22 100644
--- a/src/Datium.php
+++ b/src/Datium.php
@@ -160,7 +160,6 @@ public function __construct()
         $this->gregorian_DayofWeek = $this->date_time->format('w');
 
         $this->convert_calendar = new Convert();
-
     }
 
     /**
@@ -477,6 +476,8 @@ public function sub($value)
             new DateInterval($this->date_interval_expression)
         );
 
+        $this->gregorian_DayofWeek = $this->date_time->format('w');
+        
         return $this;
 
     }
@@ -590,7 +591,7 @@ public function timestamp()
     public function get($format = 'Y-m-d H:i:s')
     {
 
-        if( $format === 'timestamp' ) {
+        if ($format === 'timestamp') {
 
           return $this->timestamp();
 
diff --git a/tests/DatiumTest.php b/tests/DatiumTest.php
index 69e2aa6..4a492b4 100644
--- a/tests/DatiumTest.php
+++ b/tests/DatiumTest.php
@@ -252,4 +252,12 @@ public function testGregorianCalendar()
         $this->assertEquals('Saturday 25th June 2016 12:00:00 PM', $gregorian);
 
     }
+
+    public function testJalaliSubDateTime()
+    {
+        $jalali = Datium::create(2017, 9, 1, 12, 0, 0)->sub('1 day')->to('jalali')
+                        ->get('l jS F Y h:i:s');
+
+        $this->assertEquals("Panjshanbe 9th Shahrivar 1396 12:00:00", $jalali);
+    }
 }