diff --git a/README.md b/README.md
index 1a66749..6ab2ad5 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,12 @@ Add the dependency to `phpmentors/workflower` into your `composer.json` file as
 composer require phpmentors/workflower "1.4.*"
 ```
 
+when your PHP version >= 8.0, you can install `1.5.*`
+
+```
+composer require phpmentors/workflower "1.5.*"
+```
+
 **Development version:**
 
 ```
diff --git a/composer.json b/composer.json
index 20324f6..fd25ff3 100644
--- a/composer.json
+++ b/composer.json
@@ -11,12 +11,12 @@
         }
     ],
     "require": {
-        "php": "^7.1.3",
+        "php": "^8.0",
         "ext-dom": "*",
         "symfony/expression-language": "~3.4|~4.0|~5.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~6.5"
+        "phpunit/phpunit": "~8.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/tests/Workflow/ProcessInstanceTest.php b/tests/Workflow/ProcessInstanceTest.php
index 319f504..a1013fa 100644
--- a/tests/Workflow/ProcessInstanceTest.php
+++ b/tests/Workflow/ProcessInstanceTest.php
@@ -30,7 +30,7 @@ class ProcessInstanceTest extends TestCase
     /**
      * {@inheritdoc}
      */
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->workflowRepository = new WorkflowRepository();
     }