diff --git a/.github/workflows/test.Dockerfile b/.github/workflows/test.Dockerfile
index a7acaf1..f89f0cd 100644
--- a/.github/workflows/test.Dockerfile
+++ b/.github/workflows/test.Dockerfile
@@ -1,5 +1,7 @@
 ARG PHP_VERSION=latest
+ARG CODE_COVERAGE=false
 FROM php:${PHP_VERSION}-cli-alpine
+ARG CODE_COVERAGE
 
 WORKDIR /workdir
 
@@ -10,9 +12,10 @@ ENV COMPOSER_HTACCESS_PROTECT=0
 ENV COMPOSER_CACHE_DIR=/.composer
 
 # install PHP extension pcov
-RUN apk add --no-cache --virtual .build-deps $PHPIZE_DEPS \
-    && mkdir -p /usr/src/php/ext/pcov && curl -fsSL https://pecl.php.net/get/pcov | tar xvz -C /usr/src/php/ext/pcov --strip 1 \
-    && docker-php-ext-install pcov \
-    && docker-php-ext-enable pcov \
-    && rm -Rf /usr/src/php/ext/pcov \
-    && apk del --no-cache .build-deps
+RUN if [[ "${CODE_COVERAGE}" == "true" ]] ; \
+    then apk add --no-cache --virtual .build-deps $PHPIZE_DEPS linux-headers \
+      && pecl install xdebug \
+      && docker-php-ext-enable xdebug \
+      && apk del --no-cache .build-deps ; \
+    fi
+
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f3834e5..c6b4a1b 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,46 +13,61 @@ jobs:
     strategy:
       matrix:
         include:
-          - PHP_VERSION: 7.1
+          - PHP_VERSION: "7.1"
             CODE_COVERAGE: false
             RUN_PHPSTAN: false
             RUN_PSALM: false
             RUN_BENCHMARK: false
-          - PHP_VERSION: 7.2
-            CODE_COVERAGE: true
+          - PHP_VERSION: "7.2"
+            CODE_COVERAGE: false
             RUN_PHPSTAN: false
             RUN_PSALM: false
             RUN_BENCHMARK: true
-          - PHP_VERSION: 7.3
-            CODE_COVERAGE: true
+          - PHP_VERSION: "7.3"
+            CODE_COVERAGE: false
             RUN_PHPSTAN: false
             RUN_PSALM: false
             RUN_BENCHMARK: false
-          - PHP_VERSION: 7.4
-            CODE_COVERAGE: true
+          - PHP_VERSION: "7.4"
+            CODE_COVERAGE: false
             RUN_PHPSTAN: true
-            RUN_PSALM: true
+            RUN_PSALM: false
             RUN_BENCHMARK: false
-          - PHP_VERSION: 8.0
-            CODE_COVERAGE: true
+          - PHP_VERSION: "8.0"
+            CODE_COVERAGE: false
             RUN_PHPSTAN: true
-            RUN_PSALM: true
+            RUN_PSALM: false
+            RUN_BENCHMARK: false
+          - PHP_VERSION: "8.1"
+            CODE_COVERAGE: false
+            RUN_PHPSTAN: false
+            RUN_PSALM: false
             RUN_BENCHMARK: false
-          - PHP_VERSION: 8.1
+          - PHP_VERSION: "8.2"
+            CODE_COVERAGE: false
+            RUN_PHPSTAN: false
+            RUN_PSALM: false
+            RUN_BENCHMARK: true
+          - PHP_VERSION: "8.3"
             CODE_COVERAGE: true
-            RUN_PHPSTAN: true
+            RUN_PHPSTAN: false
             RUN_PSALM: true
-            RUN_BENCHMARK: true
+            RUN_BENCHMARK: false
+          - PHP_VERSION: "8.4"
+            CODE_COVERAGE: false
+            RUN_PHPSTAN: true
+            RUN_PSALM: false
+            RUN_BENCHMARK: false
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
 
       - name: Cache Docker Image
         id: cache-docker-image
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: /tmp/docker-image.tar
-          key: cache-docker-image-test:${{ matrix.PHP_VERSION }}
+          key: cache-docker-image-test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}
 
       - name: Load Docker Image
         if: steps.cache-docker-image.outputs.cache-hit == 'true'
@@ -60,10 +75,10 @@ jobs:
 
       - name: Build Docker Image
         if: steps.cache-docker-image.outputs.cache-hit != 'true'
-        run: docker build -f .github/workflows/test.Dockerfile -t 'test:${{ matrix.PHP_VERSION }}' --build-arg 'PHP_VERSION=${{ matrix.PHP_VERSION }}' .
+        run: docker build -f .github/workflows/test.Dockerfile -t 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}' --build-arg 'PHP_VERSION=${{ matrix.PHP_VERSION }}' --build-arg 'CODE_COVERAGE=${{ matrix.CODE_COVERAGE }}' .
 
       - name: Cache Composer Cache Files
-        uses: actions/cache@v2
+        uses: actions/cache@v4
         with:
           path: /tmp/composer-cache-files
           key: cache-composer-cache-files-${{ matrix.PHP_VERSION }}
@@ -75,12 +90,12 @@ jobs:
           if [ "${{ matrix.RUN_PHPSTAN }}" != "true" ]; then composer remove --dev phpstan/phpstan --no-update --no-interaction; fi
           if [ "${{ matrix.RUN_PSALM }}" != "true" ]; then composer remove --dev vimeo/psalm --no-update --no-interaction; fi
           if [ "${{ matrix.RUN_BENCHMARK }}" != "true" ]; then composer remove --dev phpbench/phpbench --no-update --no-interaction; fi
-          docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" -v '/tmp/composer-cache-files:/.composer' 'test:${{ matrix.PHP_VERSION }}' composer install --no-interaction --no-progress --prefer-dist ${{ matrix.COMPOSER_EXTRA_ARGS }}
+          docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" -v '/tmp/composer-cache-files:/.composer' 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}' composer install --no-interaction --no-progress --prefer-dist ${{ matrix.COMPOSER_EXTRA_ARGS }}
 
       - name: Run Unit Test
         run: |
           if [ "${{ matrix.CODE_COVERAGE }}" == "true" ]; then
-            docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}' php -d 'zend.assertions=1' -d 'pcov.enabled=1' ./vendor/bin/phpunit --coverage-clover=.clover.xml
+            docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}-xdebug' php -d 'zend.assertions=1' -d 'xdebug.mode=coverage' ./vendor/bin/phpunit --coverage-clover=.clover.xml
           else
             docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}' php -d 'zend.assertions=1' ./vendor/bin/phpunit
           fi
@@ -94,16 +109,16 @@ jobs:
 
       - name: Run PHPStan
         if: ${{ matrix.RUN_PHPSTAN }}
-        run: docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}' php -d 'memory_limit=2G' ./vendor/bin/phpstan analyse --level max src/ tests/
+        run: docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}' php -d 'memory_limit=2G' ./vendor/bin/phpstan analyse --level max src/ tests/
 
       - name: Run psalm
         if: ${{ matrix.RUN_PSALM }}
-        run: mkdir -p "$HOME/.cache/psalm" && docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" -v "$HOME/.cache/psalm:/.cache/psalm" 'test:${{ matrix.PHP_VERSION }}' php ./vendor/bin/psalm
+        run: mkdir -p "$HOME/.cache/psalm" && docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" -v "$HOME/.cache/psalm:/.cache/psalm" 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}' php ./vendor/bin/psalm
 
       - name: Run benchmark
         if: ${{ matrix.RUN_BENCHMARK }}
-        run: docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}' php -d 'zend.assertions=-1' ./vendor/bin/phpbench run --no-interaction --revs=1 --retry-threshold=100 --progress=none
+        run: docker run --rm -u "$(id -u):$(id -g)" -v "$(pwd):/workdir" 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}' php -d 'zend.assertions=-1' ./vendor/bin/phpbench run --no-interaction --revs=1 --retry-threshold=100 --progress=none
 
       - name: Export Docker Image
         if: steps.cache-docker-image.outputs.cache-hit != 'true'
-        run: docker save --output /tmp/docker-image.tar 'test:${{ matrix.PHP_VERSION }}'
+        run: docker save --output /tmp/docker-image.tar 'test:${{ matrix.PHP_VERSION }}${{ matrix.CODE_COVERAGE && '-xdebug' || '' }}'
diff --git a/composer.json b/composer.json
index 5749337..2ae8e4b 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,7 @@
         "phpbench/phpbench": "^0.16.10 || ^1.0.4",
         "phpstan/phpstan": "^1.3.1",
         "phpunit/phpunit": "^7.5.20 | ^8.5.22 | ^9.5.11",
-        "vimeo/psalm": "^4.17.0"
+        "vimeo/psalm": "^4.17.0 | ^5.26.1"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index bd87684..291742f 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -7,7 +7,7 @@ parameters:
         # EnumSerializableTrait
         - message: '#Access to private property \$[a-z]+ of parent class MabeEnum\\Enum#'
           path: %currentWorkingDirectory%/src/EnumSerializableTrait.php
-        - message: '#Access to an undefined static property MabeEnumTest\\TestAsset\\SerializableEnum::\$instances#'
+        - message: '#Access to private static property \$instances#'
           path: %currentWorkingDirectory%/src/EnumSerializableTrait.php
 
         # Tests
diff --git a/src/EnumMap.php b/src/EnumMap.php
index 9aa1b24..eae61ba 100644
--- a/src/EnumMap.php
+++ b/src/EnumMap.php
@@ -42,7 +42,7 @@ class EnumMap implements ArrayAccess, Countable, IteratorAggregate
      * @param null|iterable<T|null|bool|int|float|string|array<mixed>, mixed> $map Initialize map
      * @throws InvalidArgumentException
      */
-    public function __construct(string $enumeration, iterable $map = null)
+    public function __construct(string $enumeration, ?iterable $map = null)
     {
         if (!\is_subclass_of($enumeration, Enum::class)) {
             throw new InvalidArgumentException(\sprintf(
diff --git a/src/EnumSet.php b/src/EnumSet.php
index be3cd07..42e34b3 100644
--- a/src/EnumSet.php
+++ b/src/EnumSet.php
@@ -86,7 +86,7 @@ class EnumSet implements IteratorAggregate, Countable
      * @param iterable<T|null|bool|int|float|string|array<mixed>>|null $enumerators iterable list of enumerators initializing the set
      * @throws InvalidArgumentException
      */
-    public function __construct(string $enumeration, iterable $enumerators = null)
+    public function __construct(string $enumeration, ?iterable $enumerators = null)
     {
         if (!\is_subclass_of($enumeration, Enum::class)) {
             throw new InvalidArgumentException(\sprintf(
diff --git a/tests/MabeEnumTest/EnumSerializableTraitTest.php b/tests/MabeEnumTest/EnumSerializableTraitTest.php
index 17da462..5694a3c 100644
--- a/tests/MabeEnumTest/EnumSerializableTraitTest.php
+++ b/tests/MabeEnumTest/EnumSerializableTraitTest.php
@@ -108,7 +108,7 @@ private function clearEnumeration($enumeration): void
         }
 
         foreach ($reflClass->getProperties(ReflectionProperty::IS_STATIC) as $reflProp) {
-            $reflProp->setAccessible(true);;
+            $reflProp->setAccessible(true);
             $reflProp->setValue(null, []);
         }
     }
diff --git a/tests/MabeEnumTest/EnumTest.php b/tests/MabeEnumTest/EnumTest.php
index 1d04271..5156fde 100644
--- a/tests/MabeEnumTest/EnumTest.php
+++ b/tests/MabeEnumTest/EnumTest.php
@@ -40,7 +40,7 @@ private function resetStaticEnumProps(): void
         $enumPropsRefl = $enumRefl->getProperties(ReflectionProperty::IS_STATIC);
         foreach ($enumPropsRefl as $enumPropRefl) {
             $enumPropRefl->setAccessible(true);
-            $enumPropRefl->setValue([]);
+            $enumPropRefl->setValue(null, []);
         }
     }