diff --git a/CHANGELOG.md b/CHANGELOG.md
index 463f323..8594dc1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@ Latest
 ------
 
 ### Changes
+* [#51](https://github.com/cleverage/cache-process-bundle/issues/51) Use the PHP 8.3 to 8.5 functions through the Symfony polyfills ([cleverage/process-bundle#299](https://github.com/cleverage/process-bundle/issues/299)): require `symfony/polyfill-php83`, `symfony/polyfill-php84` and `symfony/polyfill-php85`. Rector is configured with the minimum supported PHP version (`withPhpVersion(PhpVersion::PHP_82)`, it used PHP 8.5 features) and `withPhpSets()` without explicit version, which applies the rules using a newer function when its polyfill is required (no change on the current code). Document it in `CONTRIBUTING.md`.
 * [#49](https://github.com/cleverage/cache-process-bundle/issues/49) Add a `CleverAge\CacheProcessBundle\Registry\AdapterRegistry` alias of the `cleverage_cache_process.registry.adapter` service: the registry can be autowired, e.g. in a custom cache task extending `AbstractCacheTask`. Update documentation, add tests.
 * [#43](https://github.com/cleverage/cache-process-bundle/issues/43) Give a code to the tasks ([cleverage/process-bundle#91](https://github.com/cleverage/process-bundle/issues/91)): `cache_get` and `cache_set` (`task: cache_get`, with `cleverage/process-bundle` 5.4 or later, referencing them by `service` being deprecated there). The tasks have their class name as service id; fetching them directly from the service container is deprecated (`container.private`), they will be private in 3.0. The former ids `cleverage_cache_process.task.get` / `cleverage_cache_process.task.set` are deprecated aliases, removed in 3.0. Update documentation, add tests.
 * [#41](https://github.com/cleverage/cache-process-bundle/issues/41) CI: test the lowest versions allowed by `composer.json` (`--prefer-lowest`, PHP 8.2).
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8222397..6bb568a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -40,6 +40,14 @@ make quality
 make tests
 ```
 
+## PHP version
+
+The bundle supports PHP 8.2 and later: do not use a syntax introduced by a later version (typed class constants,
+property hooks, pipe operator...). The functions of PHP 8.3 to 8.5 (`json_validate()`, `array_find()`, `array_any()`,
+`mb_trim()`, `array_first()`...) can be used: they are provided by the required `symfony/polyfill-php83`,
+`symfony/polyfill-php84` and `symfony/polyfill-php85` packages on the older versions. Rector (`make quality`) is
+configured accordingly.
+
 ## Deprecations notices
 
 When a feature should be deprecated, or when you have a breaking change for a future version, please :
diff --git a/composer.json b/composer.json
index 9dca794..4da4ee6 100644
--- a/composer.json
+++ b/composer.json
@@ -39,7 +39,10 @@
         "symfony/dependency-injection": "^6.4 || ^7.4 || ^8",
         "symfony/finder": "^6.4 || ^7.4 || ^8",
         "symfony/http-kernel": "^6.4 || ^7.4 || ^8",
-        "symfony/options-resolver": "^6.4 || ^7.4 || ^8"
+        "symfony/options-resolver": "^6.4 || ^7.4 || ^8",
+        "symfony/polyfill-php83": "^1.33",
+        "symfony/polyfill-php84": "^1.33",
+        "symfony/polyfill-php85": "^1.33"
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "*",
diff --git a/rector.php b/rector.php
index 97b29e1..7406cc2 100644
--- a/rector.php
+++ b/rector.php
@@ -3,23 +3,21 @@
 declare(strict_types=1);
 
 use Rector\Config\RectorConfig;
-use Rector\Set\ValueObject\LevelSetList;
 use Rector\Symfony\Set\SymfonySetList;
 use Rector\ValueObject\PhpVersion;
 
 return RectorConfig::configure()
-    ->withPhpVersion(PhpVersion::PHP_85)
+    ->withPhpVersion(PhpVersion::PHP_82)
     ->withPaths([
         __DIR__.'/src',
         __DIR__.'/tests',
     ])
-    ->withPhpSets(php82: true)
+    ->withPhpSets()
     // here we can define what prepared sets of rules will be applied
     ->withComposerBased(phpunit: true, symfony: true)
     ->withPreparedSets(deadCode: true, codeQuality: true, symfonyCodeQuality: true)
     ->withAttributesSets(symfony: true)
     ->withSets([
-        LevelSetList::UP_TO_PHP_82,
         SymfonySetList::SYMFONY_CONSTRUCTOR_INJECTION,
     ])
 ;