diff --git a/tests/_support/Helper/ValidColorValuesProvider.php b/tests/_support/Helper/ValidColorValuesProvider.php
index 60f6b67..9afe87e 100644
--- a/tests/_support/Helper/ValidColorValuesProvider.php
+++ b/tests/_support/Helper/ValidColorValuesProvider.php
@@ -30,6 +30,42 @@ class ValidColorValuesProvider
                 'value'      => 1.0,
             ],
         ],
+        'hellgrau' => [
+            self::CMYK => [
+                'cyan'    => 0.0,
+                'magenta' => 0.0,
+                'yellow'  => 0.0,
+                'key'     => 2.0 / 3.0,
+            ],
+            self::RGB  => [
+                'red'   => 1.0 / 3.0,
+                'green' => 1.0 / 3.0,
+                'blue'  => 1.0 / 3.0,
+            ],
+            self::HSV  => [
+                'hue'        => 0.0,
+                'saturation' => 0.0,
+                'value'      => 1.0 / 3.0,
+            ],
+        ],
+        'dunkelgrau' => [
+            self::CMYK => [
+                'cyan'    => 0.0,
+                'magenta' => 0.0,
+                'yellow'  => 0.0,
+                'key'     => 1.0 / 3.0,
+            ],
+            self::RGB  => [
+                'red'   => 2.0 / 3.0,
+                'green' => 2.0 / 3.0,
+                'blue'  => 2.0 / 3.0,
+            ],
+            self::HSV  => [
+                'hue'        => 0.0,
+                'saturation' => 0.0,
+                'value'      => 2.0 / 3.0,
+            ],
+        ],
         'schwarz' => [
             self::CMYK => [
                 'cyan'    => 0.0,