diff --git a/src/Transformer/Utilities/CyanMagentaYellowKeyToHueSaturationValue.php b/src/Transformer/Utilities/CyanMagentaYellowKeyToHueSaturationValue.php
index 3a52c14..ae42ca4 100644
--- a/src/Transformer/Utilities/CyanMagentaYellowKeyToHueSaturationValue.php
+++ b/src/Transformer/Utilities/CyanMagentaYellowKeyToHueSaturationValue.php
@@ -2,6 +2,7 @@
 
 namespace TorstenHettstedt\Colors\Transformer\Utilities;
 
+use JetBrains\PhpStorm\Pure;
 use TorstenHettstedt\Colors\ColorModels\CyanMagentaYellowKey;
 use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 
@@ -72,6 +73,7 @@ class CyanMagentaYellowKeyToHueSaturationValue
             ->setValue($this->value);
     }
 
+    #[Pure]
     protected function buildHueAmount(): float
     {
         // Wenn beide Werte gleich sind, ist die Endfarbe Grau.
diff --git a/src/Transformer/Utilities/RedGreenBlueToHueSaturationValue.php b/src/Transformer/Utilities/RedGreenBlueToHueSaturationValue.php
index f74d781..b4b8f9b 100644
--- a/src/Transformer/Utilities/RedGreenBlueToHueSaturationValue.php
+++ b/src/Transformer/Utilities/RedGreenBlueToHueSaturationValue.php
@@ -2,6 +2,7 @@
 
 namespace TorstenHettstedt\Colors\Transformer\Utilities;
 
+use JetBrains\PhpStorm\Pure;
 use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 use TorstenHettstedt\Colors\ColorModels\RedGreenBlue;
 
@@ -70,6 +71,7 @@ class RedGreenBlueToHueSaturationValue
             ->setValue($this->value);
     }
 
+    #[Pure]
     protected function buildHueAmount(): float
     {
         // Wenn beide Werte gleich sind, ist die Endfarbe Grau.