diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bc7690e..4df196a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -32,7 +32,4 @@ jobs:
           php-version: ${{ matrix.php }}
           coverage: xdebug
       - run: composer install
-      - run: vendor/bin/phpunit --coverage-text
-        if: ${{ matrix.php >= 7.3 }}
-      - run: vendor/bin/phpunit --coverage-text -c phpunit.xml.legacy
-        if: ${{ matrix.php < 7.3 }}
+      - run: vendor/bin/phpunit --coverage-text ${{ matrix.php < 7.3 && '-c phpunit.xml.legacy' || '' }}
diff --git a/composer.json b/composer.json
index 40dbaee..76e16f1 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
     "require-dev": {
         "clue/hexdump": "~0.2.0",
         "react/event-loop": "^1.2",
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36"
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36"
     },
     "autoload": {
         "psr-4": {
diff --git a/tests/TestCase.php b/tests/TestCase.php
index 7ccc770..94f88ff 100644
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -31,10 +31,10 @@ protected function expectCallableNever()
     protected function createCallableMock()
     {
         if (method_exists('PHPUnit\Framework\MockObject\MockBuilder', 'addMethods')) {
-            // PHPUnit 9+
+            // PHPUnit 8.5+
             return $this->getMockBuilder('stdClass')->addMethods(array('__invoke'))->getMock();
         } else {
-            // legacy PHPUnit 4 - PHPUnit 8
+            // legacy PHPUnit 4 - PHPUnit 8.4
             return $this->getMockBuilder('stdClass')->setMethods(array('__invoke'))->getMock();
         }
     }