diff --git a/tests/ChecksumBarcodeTest.php b/tests/ChecksumBarcodeTest.php
index 2bbf0db..4298211 100644
--- a/tests/ChecksumBarcodeTest.php
+++ b/tests/ChecksumBarcodeTest.php
@@ -1,13 +1,14 @@
 <?php
 
 use PHPUnit\Framework\TestCase;
+use Picqer\Barcode\Exceptions\InvalidCheckDigitException;
 use Picqer\Barcode\Types\TypeEan13;
 use Picqer\Barcode\Types\TypeInterface;
 use Picqer\Barcode\Types\TypeITF14;
 
 class ChecksumBarcodeTest extends TestCase
 {
-    public static $supportedBarcodes = [
+    private const VALID_BARCODES = [
         ['type' => TypeEan13::class, 'barcodes' => [
             '081231723897' => '0812317238973',
             '004900000463' => '0049000004632',
@@ -17,14 +18,30 @@ class ChecksumBarcodeTest extends TestCase
             '0540014128876' => '05400141288766',
         ]],
     ];
+    private const INVALID_BARCODES = [
+        ['type' => TypeEan13::class, 'barcodes' => ['0812317238972', '0049000004633']],
+        ['type' => TypeITF14::class, 'barcodes' => ['00012345600016', '05400141288762']],
+    ];
+
+    public function testAllValidBarcodeTypes()
+    {
+        foreach (self::VALID_BARCODES as $barcodeTestSet) {
+            $barcodeType = $this->getBarcodeType($barcodeTestSet['type']);
+
+            foreach ($barcodeTestSet['barcodes'] as $testBarcode => $validBarcode) {
+                $this->assertEquals($validBarcode, $barcodeType->getBarcodeData($testBarcode)->getBarcode());
+            }
+        }
+    }
 
-    public function testAllSupportedBarcodeTypes()
+    public function testAllInvalidBarcodeTypes()
     {
-        foreach ($this::$supportedBarcodes as $barcodeTestSet) {
+        foreach (self::INVALID_BARCODES as $barcodeTestSet) {
             $barcodeType = $this->getBarcodeType($barcodeTestSet['type']);
 
-            foreach ($barcodeTestSet['barcodes'] as $testBarcode => $expectedBarcode) {
-                $this->assertEquals($expectedBarcode, $barcodeType->getBarcodeData($testBarcode)->getBarcode());
+            foreach ($barcodeTestSet['barcodes'] as $invalidBarcode) {
+                $this->expectException(InvalidCheckDigitException::class);
+                $barcodeType->getBarcodeData($invalidBarcode)->getBarcode();
             }
         }
     }