diff --git a/Makefile b/Makefile
index 4ad0ad6..1b9191f 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ phpmd-ci: prepare-ci ## Run PHP Mess Detector (CI)
 	PHPMD_FORMAT="github" $(MAKE) phpmd
 .PHONY: phpmd phpmd-ci
 
-PHPSTAN_LEVEL ?= max
+PHPSTAN_LEVEL ?= 9
 phpstan: ## Run PHPStan
 	vendor/bin/phpstan analyse --configuration=phpstan.neon --memory-limit=-1 --level=$(PHPSTAN_LEVEL) $(EXTRA_ARGS) src tests
 phpstan-ci: prepare-ci ## Run PHPStan (CI)
diff --git a/composer.json b/composer.json
index 1c58b7d..2ad8706 100644
--- a/composer.json
+++ b/composer.json
@@ -4,15 +4,16 @@
   "type": "phpcodesniffer-standard",
   "license": "MIT",
   "require": {
-    "php": "^8.3",
-    "squizlabs/php_codesniffer": "^3.8",
-    "slevomat/coding-standard": "^8.14",
+    "php": "^8.4",
+    "squizlabs/php_codesniffer": "^4.0",
+    "slevomat/coding-standard": "^8.24",
     "phpmd/phpmd": "^2.15",
-    "phpstan/phpstan": "^1.10",
-    "phpstan/phpstan-phpunit": "^1.3",
-    "jangregor/phpstan-prophecy": "^1.0",
-    "phpspec/prophecy-phpunit": "^2.1",
-    "phpunit/phpunit": "^10.5 || ^11.0"
+    "phpstan/phpstan": "^2.1",
+    "phpstan/phpstan-phpunit": "^2.0",
+    "phpstan/phpstan-symfony": "^2.0",
+    "jangregor/phpstan-prophecy": "^2.2",
+    "phpspec/prophecy-phpunit": "^2.4",
+    "phpunit/phpunit": "^11.0 || ^12.4"
   },
   "require-dev": {
     "roave/security-advisories": "dev-latest"
diff --git a/lib/phpcs/rules/base.xml b/lib/phpcs/rules/base.xml
index 0e999cb..cf41548 100644
--- a/lib/phpcs/rules/base.xml
+++ b/lib/phpcs/rules/base.xml
@@ -26,27 +26,26 @@
     <!-- Forbid alias functions, i.e. `sizeof()`, `delete()` -->
     <rule ref="Generic.PHP.ForbiddenFunctions">
         <properties>
-            <property name="forbiddenFunctions" type="array"
-                      value="
-                    chop => rtrim,
-                    close => closedir,
-                    delete => unset,
-                    doubleval => floatval,
-                    fputs => fwrite,
-                    ini_alter => ini_set,
-                    is_double => is_float,
-                    is_integer => is_int,
-                    is_long => is_int,
-                    is_null => null,
-                    is_real => is_float,
-                    is_writeable => is_writable,
-                    join => implode,
-                    key_exists => array_key_exists,
-                    pos => current,
-                    show_source => highlight_file,
-                    sizeof => count,
-                    strchr => strstr
-                "/>
+            <property name="forbiddenFunctions" type="array">
+                <element key="chop" value="rtrim" />
+                <element key="close" value="closedir" />
+                <element key="delete" value="unset" />
+                <element key="doubleval" value="floatval" />
+                <element key="fputs" value="fwrite" />
+                <element key="ini_alter" value="ini_set" />
+                <element key="is_double" value="is_float" />
+                <element key="is_integer" value="is_int" />
+                <element key="is_long" value="is_int" />
+                <element key="is_null" value="null" />
+                <element key="is_real" value="is_float" />
+                <element key="is_writeable" value="is_writable" />
+                <element key="join" value="implode" />
+                <element key="key_exists" value="array_key_exists" />
+                <element key="pos" value="current" />
+                <element key="show_source" value="highlight_file" />
+                <element key="sizeof" value="count" />
+                <element key="strchr" value="strstr" />
+            </property>
         </properties>
     </rule>
     <!-- Forbid useless inline string concatenation -->
diff --git a/lib/phpcs/rules/slevomat.xml b/lib/phpcs/rules/slevomat.xml
index 7096ec5..bfead2a 100644
--- a/lib/phpcs/rules/slevomat.xml
+++ b/lib/phpcs/rules/slevomat.xml
@@ -235,10 +235,10 @@
         <exclude name="SlevomatCodingStandard.TypeHints.ReturnTypeHint.MissingTraversableTypeHintSpecification" />
     </rule>
     <!-- Checks format of union type hints. -->
-    <rule ref="SlevomatCodingStandard.TypeHints.UnionTypeHintFormat">
+    <rule ref="SlevomatCodingStandard.TypeHints.DNFTypeHintFormat">
         <properties>
             <!-- Union type must be separated by | without spaces -->
-            <property name="withSpaces" value="no"/>
+            <property name="withSpacesAroundOperators" value="no"/>
         </properties>
     </rule>
     <!-- Reports useless @var annotation (or whole documentation comment) for constants because the type of constant is always clear. -->