diff --git a/composer.json b/composer.json
index 8cce282..7e8f131 100644
--- a/composer.json
+++ b/composer.json
@@ -22,11 +22,13 @@
     },
     "require": {
         "php": "^8.0",
-        "phpunit/php-code-coverage": "^9.2"
+        "phpunit/php-code-coverage": "^9.2",
+        "jetbrains/phpstorm-attributes": "^1.0.0"
     },
     "require-dev": {
         "codeception/codeception": "^4.1.18",
         "codeception/module-phpbrowser": "^1.0.0",
-        "codeception/module-asserts": "^1.0.0"
+        "codeception/module-asserts": "^1.0.0",
+        "phpstan/phpstan" : "^0.12.82"
     }
 }
diff --git a/phpstan.neon b/phpstan.neon
new file mode 100644
index 0000000..c1923db
--- /dev/null
+++ b/phpstan.neon
@@ -0,0 +1,6 @@
+parameters:
+	level: 6
+	paths:
+		- src
+		- tests/unit
+		- tests/_support/Helper
\ No newline at end of file
diff --git a/src/ColorModels/AbstractColorModel.php b/src/ColorModels/AbstractColorModel.php
index 5db61f3..4e85a57 100644
--- a/src/ColorModels/AbstractColorModel.php
+++ b/src/ColorModels/AbstractColorModel.php
@@ -8,7 +8,7 @@ use InvalidArgumentException;
 abstract class AbstractColorModel
 {
 
-    protected function checkValue(float $value)
+    protected function checkValue(float $value): void
     {
         if ($value > 1.0) {
             throw new InvalidArgumentException('Ein Wert größer als 1 ist nicht definierbar.');
diff --git a/src/Transformer/Utilities/AbstractHueSaturationValueToUtility.php b/src/Transformer/Utilities/AbstractHueSaturationValueToUtility.php
new file mode 100644
index 0000000..d578fe5
--- /dev/null
+++ b/src/Transformer/Utilities/AbstractHueSaturationValueToUtility.php
@@ -0,0 +1,61 @@
+<?php
+
+
+namespace TorstenHettstedt\Colors\Transformer\Utilities;
+
+
+use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
+
+abstract class AbstractHueSaturationValueToUtility
+{
+    /** @var int : Größe des Intervals in 1/100 Grad */
+    protected const INTERVAL = 60.0 * 100.0;
+
+    // Daten für HSV
+    /** @var float : Definition des Farbton als Anteil eines Vollkreises '$Hue * π' */
+    protected float $hue;
+    /** @var float : Anteil am Vollkreis in 1/100 Grad  */
+    protected float $hueAsPercentGrad;
+    /** @var float : Definition der Sättigung der Farbe */
+    protected float $saturation;
+    /** @var float : Definition der Helligkeit der Farbe */
+    protected float $value;
+
+    /**
+     * HueSaturationValueToRedGreenBlue constructor.
+     * @param HueSaturationValue $from_color
+     * @noinspection PhpPureAttributeCanBeAddedInspection
+     */
+    public function __construct(HueSaturationValue $from_color)
+    {
+        $this->hue = $from_color->getHue();
+        $this->hueAsPercentGrad = intval($this->hue * self::INTERVAL * 6.0);
+        $this->saturation = $from_color->getSaturation();
+        $this->value = $from_color->getValue();
+    }
+
+
+    protected function processConvert(): void
+    {
+        if ($this->saturation > 0.0) {
+            $this->splitColor();
+        }
+    }
+
+    abstract protected function splitColor(): void;
+
+    /**
+     * @param bool $reciprocal
+     *
+     * @return float
+     */
+    protected function calcColorValue($reciprocal = false): float
+    {
+        // Rest-Anteil am Vollkreis des aktuellen Intervals als Wert '[0,1]'
+        $remainder_grad = $this->hueAsPercentGrad % self::INTERVAL;
+        // Rest-Anteil am Vollkreis des aktuellen Intervals als Wert '[0,1]'
+        $remainder = $remainder_grad / self::INTERVAL;
+        return $this->saturation * ($reciprocal ? (1 - $remainder) : $remainder);
+    }
+
+}
\ No newline at end of file
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/HueSaturationValueToCyanMagentaYellowKey.php b/src/Transformer/Utilities/HueSaturationValueToCyanMagentaYellowKey.php
index a8e9d0a..c66e963 100644
--- a/src/Transformer/Utilities/HueSaturationValueToCyanMagentaYellowKey.php
+++ b/src/Transformer/Utilities/HueSaturationValueToCyanMagentaYellowKey.php
@@ -5,23 +5,9 @@ namespace TorstenHettstedt\Colors\Transformer\Utilities;
 
 
 use TorstenHettstedt\Colors\ColorModels\CyanMagentaYellowKey;
-use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 
-class HueSaturationValueToCyanMagentaYellowKey
+class HueSaturationValueToCyanMagentaYellowKey extends AbstractHueSaturationValueToUtility
 {
-    /** @var int : Größe des Intervals in 1/100 Grad */
-    protected const INTERVAL = 60.0 * 100.0;
-
-    // Daten für HSV
-    /** @var float : Definition des Farbton als Anteil eines Vollkreises '$Hue * π' */
-    protected float $hue;
-    /** @var float : Anteil am Vollkreis in 1/100 Grad  */
-    protected float $hueAsPercentGrad;
-    /** @var float : Definition der Sättigung der Farbe */
-    protected float $saturation;
-    /** @var float : Definition der Helligkeit der Farbe */
-    protected float $value;
-
     // Daten für CMYK
     /** @var float : Definition des Cyan-Anteil */
     protected float $cyan = 0.0;
@@ -32,19 +18,6 @@ class HueSaturationValueToCyanMagentaYellowKey
     /** @var float : Definition des Schwarzanteil */
     protected float $key = 0.0;
 
-    /**
-     * HueSaturationValueToRedGreenBlue constructor.
-     * @param HueSaturationValue $from_color
-     * @noinspection PhpPureAttributeCanBeAddedInspection
-     */
-    public function __construct(HueSaturationValue $from_color)
-    {
-        $this->hue = $from_color->getHue();
-        $this->hueAsPercentGrad = intval($this->hue * self::INTERVAL * 6);
-        $this->saturation = $from_color->getSaturation();
-        $this->value = $from_color->getValue();
-    }
-
     public function convert(): CyanMagentaYellowKey
     {
         $this->processConvert();
@@ -60,17 +33,15 @@ class HueSaturationValueToCyanMagentaYellowKey
     protected function processConvert(): void
     {
         $this->key = 1 - $this->value;
-        if ($this->saturation !== 0.0) {
-            $this->splitColor();
-        }
+        parent::processConvert();
     }
 
     protected function splitColor(): void
     {
         // ID des zu nutzenden Interval
-        $interval_id = intdiv($this->hueAsPercentGrad , self::INTERVAL);
+        $interval_id = $this->hueAsPercentGrad / self::INTERVAL;
 
-        switch ($interval_id) {
+        switch ((int)$interval_id) {
             case 1: // Yellow
                 $this->cyan = $this->calcColorValue();
                 $this->yellow = $this->saturation;
@@ -98,13 +69,4 @@ class HueSaturationValueToCyanMagentaYellowKey
         }
     }
 
-    protected function calcColorValue($reciprocal = false): float
-    {
-        // Rest-Anteil am Vollkreis des aktuellen Intervals als Wert '[0,1]'
-        $remainder_grad = $this->hueAsPercentGrad % self::INTERVAL;
-        // Rest-Anteil am Vollkreis des aktuellen Intervals als Wert '[0,1]'
-        $remainder = $remainder_grad / self::INTERVAL;
-        return $this->saturation * ($reciprocal ? (1 - $remainder) : $remainder);
-    }
-
 }
\ No newline at end of file
diff --git a/src/Transformer/Utilities/HueSaturationValueToRedGreenBlue.php b/src/Transformer/Utilities/HueSaturationValueToRedGreenBlue.php
index 64fab92..3520d92 100644
--- a/src/Transformer/Utilities/HueSaturationValueToRedGreenBlue.php
+++ b/src/Transformer/Utilities/HueSaturationValueToRedGreenBlue.php
@@ -4,24 +4,10 @@
 namespace TorstenHettstedt\Colors\Transformer\Utilities;
 
 
-use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 use TorstenHettstedt\Colors\ColorModels\RedGreenBlue;
 
-class HueSaturationValueToRedGreenBlue
+class HueSaturationValueToRedGreenBlue extends AbstractHueSaturationValueToUtility
 {
-    /** @var int : Größe des Intervals in 1/100 Grad */
-    protected const INTERVAL = 60.0 * 100.0;
-
-    // Daten für HSV
-    /** @var float : Definition des Farbton als Anteil eines Vollkreises '$Hue * π' */
-    protected float $hue;
-    /** @var float : Anteil am Vollkreis in 1/100 Grad  */
-    protected float $hueAsPercentGrad;
-    /** @var float : Definition der Sättigung der Farbe */
-    protected float $saturation;
-    /** @var float : Definition der Helligkeit der Farbe */
-    protected float $value;
-
     // Daten für RGB
     /** @var float : Definition des Rotanteil */
     protected float $red = 1.0;
@@ -30,19 +16,6 @@ class HueSaturationValueToRedGreenBlue
     /** @var float : Definition des Blauanteil */
     protected float $blue = 1.0;
 
-    /**
-     * HueSaturationValueToRedGreenBlue constructor.
-     * @param HueSaturationValue $from_color
-     * @noinspection PhpPureAttributeCanBeAddedInspection
-     */
-    public function __construct(HueSaturationValue $from_color)
-    {
-        $this->hue = $from_color->getHue();
-        $this->hueAsPercentGrad = intval($this->hue * self::INTERVAL * 6);
-        $this->saturation = $from_color->getSaturation();
-        $this->value = $from_color->getValue();
-    }
-
     public function convert(): RedGreenBlue
     {
         $this->processConvert();
@@ -57,19 +30,17 @@ class HueSaturationValueToRedGreenBlue
     protected function processConvert(): void
     {
         $this->red = $this->green = $this->blue = $this->value;
-        if ($this->saturation > 0.0) {
-            $this->splitColor();
-        }
+        parent::processConvert();
     }
 
     protected function splitColor(): void
     {
         // ID des zu nutzenden Interval
-        $interval_id = intdiv($this->hueAsPercentGrad , self::INTERVAL);
+        $interval_id = $this->hueAsPercentGrad / self::INTERVAL;
         // Ist der Wert der entgegen gesetzten Farbe.
         $opposite_color_value = $this->value * ( 1 - $this->saturation);
-        
-        switch ($interval_id) {
+
+        switch ((int)$interval_id) {
             case 1:
                 $this->red = $this->calcColorValue();
                 $this->blue = $opposite_color_value;
@@ -99,12 +70,8 @@ class HueSaturationValueToRedGreenBlue
 
     protected function calcColorValue($reciprocal = false): float
     {
-        // Rest-Anteil am Vollkreis in 1/100 Grad
-        $remainder_grad = $this->hueAsPercentGrad % self::INTERVAL;
-        // Rest-Anteil am Vollkreis des aktuellen Intervals als Wert '[0,1]'
-        $remainder = $remainder_grad / self::INTERVAL;
         $color_value = $this->value;
-        $color_value *= 1 - ($this->saturation * ($reciprocal ? (1 - $remainder) : $remainder));
+        $color_value *= 1 - parent::calcColorValue($reciprocal);
         return $color_value;
     }
 
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.
diff --git a/tests/_support/Helper/ValidColorValuesProvider.php b/tests/_support/Helper/ValidColorValuesProvider.php
index 352e669..58680d7 100644
--- a/tests/_support/Helper/ValidColorValuesProvider.php
+++ b/tests/_support/Helper/ValidColorValuesProvider.php
@@ -11,6 +11,9 @@ class ValidColorValuesProvider
     const RGB  = 'rgb';
     const HSV  = 'hsv';
 
+    /**
+     * @var array<string, array<string, float>[]>
+     */
     protected array $definitions = [
         'weiß'    => [
             self::CMYK => [
@@ -302,6 +305,11 @@ class ValidColorValuesProvider
         ],
     ];
 
+    /**
+     * @param array<string> $order
+     *
+     * @return array<string, array<string, float>[]>
+     */
     public function getValidColorValues(array $order): array
     {
         $values = [];
diff --git a/tests/unit/ColorModels/AbstractColorModelUnit.php b/tests/unit/ColorModels/AbstractColorModelUnit.php
index 90fe58e..bf23ddd 100644
--- a/tests/unit/ColorModels/AbstractColorModelUnit.php
+++ b/tests/unit/ColorModels/AbstractColorModelUnit.php
@@ -8,7 +8,7 @@ use Codeception\Test\Unit;
 abstract class AbstractColorModelUnit extends Unit
 {
 
-    abstract public function testConstruct();
+    abstract public function testConstruct(): void;
 
     /**
      * @return float[][]
diff --git a/tests/unit/ColorModels/CyanMagentaYellowKeyTest.php b/tests/unit/ColorModels/CyanMagentaYellowKeyTest.php
index bffb391..5529b8e 100644
--- a/tests/unit/ColorModels/CyanMagentaYellowKeyTest.php
+++ b/tests/unit/ColorModels/CyanMagentaYellowKeyTest.php
@@ -8,7 +8,7 @@ use TorstenHettstedt\Colors\ColorModels\CyanMagentaYellowKey;
 class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
 {
 
-    public function testConstruct()
+    public function testConstruct(): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -23,7 +23,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetCyanWithValidValue(float $value)
+    public function testSetCyanWithValidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -36,7 +36,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetMagentaWithValidValue(float $value)
+    public function testSetMagentaWithValidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -49,7 +49,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetYellowWithValidValue(float $value)
+    public function testSetYellowWithValidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -62,7 +62,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetKeyWithValidValue(float $value)
+    public function testSetKeyWithValidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -75,7 +75,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetCyanWithInvalidValue(float $value)
+    public function testSetCyanWithInvalidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -88,7 +88,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetMagentaWithInvalidValue(float $value)
+    public function testSetMagentaWithInvalidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -101,7 +101,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetYellowWithInvalidValue(float $value)
+    public function testSetYellowWithInvalidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
@@ -114,7 +114,7 @@ class CyanMagentaYellowKeyTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetKeyWithInvalidValue(float $value)
+    public function testSetKeyWithInvalidValue(float $value): void
     {
         $color = new CyanMagentaYellowKey();
 
diff --git a/tests/unit/ColorModels/HueSaturationValueTest.php b/tests/unit/ColorModels/HueSaturationValueTest.php
index 6600266..e30ba79 100644
--- a/tests/unit/ColorModels/HueSaturationValueTest.php
+++ b/tests/unit/ColorModels/HueSaturationValueTest.php
@@ -8,7 +8,7 @@ use TorstenHettstedt\Colors\ColorModels\HueSaturationValue;
 class HueSaturationValueTest extends AbstractColorModelUnit
 {
 
-    public function testConstruct()
+    public function testConstruct(): void
     {
         $color = new HueSaturationValue();
 
@@ -22,7 +22,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetHueWithValidValue(float $value)
+    public function testSetHueWithValidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
@@ -35,7 +35,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetHueWithInvalidValue(float $value)
+    public function testSetHueWithInvalidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
@@ -48,7 +48,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetSaturationWithValidValue(float $value)
+    public function testSetSaturationWithValidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
@@ -61,7 +61,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetSaturationWithInvalidValue(float $value)
+    public function testSetSaturationWithInvalidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
@@ -74,7 +74,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetValueWithValidValue(float $value)
+    public function testSetValueWithValidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
@@ -87,7 +87,7 @@ class HueSaturationValueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetValueWithInvalidValue(float $value)
+    public function testSetValueWithInvalidValue(float $value): void
     {
         $color = new HueSaturationValue();
 
diff --git a/tests/unit/ColorModels/RedGreenBlueTest.php b/tests/unit/ColorModels/RedGreenBlueTest.php
index e8de492..f0af84d 100644
--- a/tests/unit/ColorModels/RedGreenBlueTest.php
+++ b/tests/unit/ColorModels/RedGreenBlueTest.php
@@ -8,7 +8,7 @@ use TorstenHettstedt\Colors\ColorModels\RedGreenBlue;
 class RedGreenBlueTest extends AbstractColorModelUnit
 {
 
-    public function testConstruct()
+    public function testConstruct(): void
     {
         $color = new RedGreenBlue();
 
@@ -22,7 +22,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetRedWithValidValue(float $value)
+    public function testSetRedWithValidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
@@ -35,7 +35,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetRedWithInvalidValue(float $value)
+    public function testSetRedWithInvalidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
@@ -47,7 +47,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetGreenWithValidValue(float $value)
+    public function testSetGreenWithValidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
@@ -60,7 +60,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetGreenWithInvalidValue(float $value)
+    public function testSetGreenWithInvalidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
@@ -73,7 +73,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider validValueProvider
      */
-    public function testSetBlueWithValidValue(float $value)
+    public function testSetBlueWithValidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
@@ -86,7 +86,7 @@ class RedGreenBlueTest extends AbstractColorModelUnit
      *
      * @dataProvider invalidValueProvider
      */
-    public function testSetBlueWithInvalidValue(float $value)
+    public function testSetBlueWithInvalidValue(float $value): void
     {
         $color = new RedGreenBlue();
 
diff --git a/tests/unit/Transformer/CyanMagentaYellowKeyTransformerTest.php b/tests/unit/Transformer/CyanMagentaYellowKeyTransformerTest.php
index 36ad76e..26a00db 100644
--- a/tests/unit/Transformer/CyanMagentaYellowKeyTransformerTest.php
+++ b/tests/unit/Transformer/CyanMagentaYellowKeyTransformerTest.php
@@ -16,7 +16,7 @@ class CyanMagentaYellowKeyTransformerTest extends Unit
     protected CyanMagentaYellowKey $color;
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validRgbValuesProvider(): array
     {
@@ -27,7 +27,7 @@ class CyanMagentaYellowKeyTransformerTest extends Unit
     }
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validHsvValuesProvider(): array
     {
@@ -38,14 +38,14 @@ class CyanMagentaYellowKeyTransformerTest extends Unit
     }
 
     /**
-     * @param array $cmyk
-     * @param array $rgb
+     * @param array<string, float> $cmyk
+     * @param array<string, float> $rgb
      *
      * @dataProvider validRgbValuesProvider
      *
      * @throws Exception
      */
-    public function testToRedGreenBlue(array $cmyk, array $rgb)
+    public function testToRedGreenBlue(array $cmyk, array $rgb): void
     {
         $this->color = $this->make(CyanMagentaYellowKey::class, $cmyk);
 
@@ -60,13 +60,13 @@ class CyanMagentaYellowKeyTransformerTest extends Unit
     }
 
     /**
-     * @param array $cmyk
+     * @param array<string, float> $cmyk
      *
      * @dataProvider validRgbValuesProvider
      *
      * @throws Exception
      */
-    public function testToCyanMagentaYellowKey(array $cmyk)
+    public function testToCyanMagentaYellowKey(array $cmyk): void
     {
 
         $this->color = $this->make(CyanMagentaYellowKey::class, $cmyk);
@@ -82,15 +82,15 @@ class CyanMagentaYellowKeyTransformerTest extends Unit
     }
 
     /**
-     * @param array $cmyk
-     * @param array $hsv
+     * @param array<string, float> $cmyk
+     * @param array<string, float> $hsv
      *
      * @throws Exception
      *
      * @dataProvider validHsvValuesProvider
      *
      */
-    public function testToHueSaturationValue(array $cmyk, array $hsv)
+    public function testToHueSaturationValue(array $cmyk, array $hsv): void
     {
         $this->color = $this->make(CyanMagentaYellowKey::class, $cmyk);
 
diff --git a/tests/unit/Transformer/HueSaturationValueTransformerTest.php b/tests/unit/Transformer/HueSaturationValueTransformerTest.php
index 6d214ed..4f2633a 100644
--- a/tests/unit/Transformer/HueSaturationValueTransformerTest.php
+++ b/tests/unit/Transformer/HueSaturationValueTransformerTest.php
@@ -16,7 +16,7 @@ class HueSaturationValueTransformerTest extends Unit
     protected HueSaturationValue $color;
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validCmykValuesProvider(): array
     {
@@ -27,7 +27,7 @@ class HueSaturationValueTransformerTest extends Unit
     }
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validRgbValuesProvider(): array
     {
@@ -38,14 +38,14 @@ class HueSaturationValueTransformerTest extends Unit
     }
 
     /**
-     * @param array $hsv
-     * @param array $rgb
+     * @param array<string, float> $hsv
+     * @param array<string, float> $rgb
      *
      * @dataProvider validRgbValuesProvider
      *
      * @throws Exception
      */
-    public function testToRedGreenBlue(array $hsv, array $rgb)
+    public function testToRedGreenBlue(array $hsv, array $rgb): void
     {
         $this->color = $this->make(HueSaturationValue::class, $hsv);
 
@@ -60,14 +60,14 @@ class HueSaturationValueTransformerTest extends Unit
     }
 
     /**
-     * @param array $hsv
-     * @param array $cmyk
+     * @param array<string, float> $hsv
+     * @param array<string, float> $cmyk
      *
      * @throws Exception
      * @dataProvider validCmykValuesProvider
      *
      */
-    public function testToCyanMagentaYellowKey(array $hsv, array $cmyk)
+    public function testToCyanMagentaYellowKey(array $hsv, array $cmyk): void
     {
 
         $this->color = $this->make(HueSaturationValue::class, $hsv);
@@ -83,12 +83,12 @@ class HueSaturationValueTransformerTest extends Unit
     }
 
     /**
-     * @param array $hsv
+     * @param array<string, float> $hsv
      *
      * @throws Exception
      * @dataProvider validCmykValuesProvider
      */
-    public function testToHueSaturationValue(array $hsv)
+    public function testToHueSaturationValue(array $hsv): void
     {
         $this->color = $this->make(HueSaturationValue::class, $hsv);
 
diff --git a/tests/unit/Transformer/RedGreenBlueTransformerTest.php b/tests/unit/Transformer/RedGreenBlueTransformerTest.php
index d2f40a3..b42b4cd 100644
--- a/tests/unit/Transformer/RedGreenBlueTransformerTest.php
+++ b/tests/unit/Transformer/RedGreenBlueTransformerTest.php
@@ -16,7 +16,7 @@ class RedGreenBlueTransformerTest extends Unit
     protected RedGreenBlue $color;
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validCmykValuesProvider(): array
     {
@@ -27,7 +27,7 @@ class RedGreenBlueTransformerTest extends Unit
     }
 
     /**
-     * @return float[][][]
+     * @return array<string, array<string, float>[]>
      */
     public function validHsvValuesProvider(): array
     {
@@ -38,13 +38,13 @@ class RedGreenBlueTransformerTest extends Unit
     }
 
     /**
-     * @param array $rgb
+     * @param array<string, float> $rgb
      *
      * @dataProvider validCmykValuesProvider
      *
      * @throws Exception
      */
-    public function testToRedGreenBlue(array $rgb)
+    public function testToRedGreenBlue(array $rgb): void
     {
         $this->color = $this->make(RedGreenBlue::class, $rgb);
 
@@ -59,14 +59,14 @@ class RedGreenBlueTransformerTest extends Unit
     }
 
     /**
-     * @param array $rgb
-     * @param array $cmyk
+     * @param array<string, float> $rgb
+     * @param array<string, float> $cmyk
      *
      * @throws Exception
      * @dataProvider validCmykValuesProvider
      *
      */
-    public function testToCyanMagentaYellowKey(array $rgb, array $cmyk)
+    public function testToCyanMagentaYellowKey(array $rgb, array $cmyk): void
     {
 
         $this->color = $this->make(RedGreenBlue::class, $rgb);
@@ -82,13 +82,13 @@ class RedGreenBlueTransformerTest extends Unit
     }
 
     /**
-     * @param array $rgb
-     * @param array $hsv
+     * @param array<string, float> $rgb
+     * @param array<string, float> $hsv
      *
      * @throws Exception
      * @dataProvider validHsvValuesProvider
      */
-    public function testToHueSaturationValue(array $rgb, array $hsv)
+    public function testToHueSaturationValue(array $rgb, array $hsv): void
     {
         $this->color = $this->make(RedGreenBlue::class, $rgb);