diff --git a/src/Generator/EdifactDate.php b/src/Generator/EdifactDate.php
index 7b23986..c7856a1 100755
--- a/src/Generator/EdifactDate.php
+++ b/src/Generator/EdifactDate.php
@@ -16,7 +16,7 @@ class EdifactDate
     public const DATETIME_FORMAT = 'YmdHi';
 
     public const SHIPPING_WEEK = 616;
-    public const SHIPPING_WEEK_FORMAT = 'YW';
+    public const SHIPPING_WEEK_FORMAT = 'oW';
 
     public const SHIPPING_UNDEFINED = 999;
     public const SHIPPING_UNDEFINED_FORMAT = "";
diff --git a/tests/GeneratorTest/EdifactDateTest.php b/tests/GeneratorTest/EdifactDateTest.php
index 52e7a81..650ae43 100755
--- a/tests/GeneratorTest/EdifactDateTest.php
+++ b/tests/GeneratorTest/EdifactDateTest.php
@@ -61,4 +61,17 @@ public function testParseTimeFormat()
             EdifactDate::parseFormat('2018-01-23 10:00', EdifactDate::DATETIME)
         );
     }
+
+    public function testShippingWeekUsesTheWeekYear()
+    {
+        // 30 December 2024 is a Monday in ISO week 1 of 2025.
+        $this->assertEquals(
+            '202501',
+            EdifactDate::get('2024-12-30', EdifactDate::SHIPPING_WEEK)
+        );
+        $this->assertEquals(
+            '202001',
+            EdifactDate::get('2020-01-01', EdifactDate::SHIPPING_WEEK)
+        );
+    }
 }