diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7a309f1..e1c5e00 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,6 +40,7 @@ jobs:
           - highest
         php-version:
           - '8.4'
+          - '8.5'
 
     steps:
       - name: Checkout
diff --git a/README.md b/README.md
index 454920f..c8806e1 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
 Immutable objects in PHP
 -----------------
-This library provides native immutable objects for PHP>=8.4
+This library provides native immutable objects for PHP 8.4 and 8.5
 
-[![Build Status](https://img.shields.io/travis/com/lisachenko/immutable-object/master)](https://travis-ci.org/lisachenko/immutable-object)
+[![CI](https://github.com/lisachenko/immutable-object/actions/workflows/ci.yml/badge.svg)](https://github.com/lisachenko/immutable-object/actions/workflows/ci.yml)
 [![GitHub release](https://img.shields.io/github/release/lisachenko/immutable-object.svg)](https://github.com/lisachenko/immutable-object/releases/latest)
-[![Minimum PHP Version](http://img.shields.io/badge/php-%3E%3D%208.4-8892BF.svg)](https://php.net/)
+[![PHP Version](https://img.shields.io/badge/php-8.4%20%7C%208.5-8892BF.svg)](https://php.net/)
 [![License](https://img.shields.io/packagist/l/lisachenko/immutable-object.svg)](https://packagist.org/packages/lisachenko/immutable-object)
 
 Rationale
@@ -24,7 +24,8 @@ of the PHP itself.
 
 Pre-requisites and initialization
 --------------
-As this library depends on `FFI`, it requires PHP>=8.4 and `FFI` extension to be enabled.
+As this library depends on `FFI`, it requires PHP 8.4 or 8.5 and `FFI` extension to be enabled. The matching
+`lisachenko/z-engine` line (`8.4.x-dev` on PHP 8.4, `8.5.x-dev` on PHP 8.5) is resolved by Composer automatically.
 
 To install this library, simply add it via `composer`:
 ```bash
diff --git a/composer.json b/composer.json
index 70a593d..fcfecb4 100644
--- a/composer.json
+++ b/composer.json
@@ -9,11 +9,12 @@
             "email": "lisachenko.it@gmail.com"
         }
     ],
-    "minimum-stability": "stable",
+    "minimum-stability": "dev",
+    "prefer-stable": true,
     "require": {
-        "php": "~8.4.0",
+        "php": "^8.4",
         "ext-ffi": "*",
-        "lisachenko/z-engine": "~8.4.0"
+        "lisachenko/z-engine": "8.4.x-dev || 8.5.x-dev"
     },
     "require-dev": {
         "phpunit/phpunit": "^12.2"