diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0115f68..741dede 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,10 +7,11 @@ on:
 jobs:
   PHPUnit:
     name: PHPUnit (PHP ${{ matrix.php }})
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         php:
+          - 8.3
           - 8.2
           - 8.1
           - 8.0
@@ -24,7 +25,7 @@ jobs:
           - 5.4
           - 5.3
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php }}
@@ -37,13 +38,16 @@ jobs:
 
   PHPUnit-hhvm:
     name: PHPUnit (HHVM)
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-22.04
     continue-on-error: true
     steps:
-      - uses: actions/checkout@v2
-      - uses: azjezz/setup-hhvm@v1
+      - uses: actions/checkout@v4
+      - run: cp "$(which composer)" composer.phar && ./composer.phar self-update --2.2 # downgrade Composer for HHVM
+      - name: Run hhvm composer.phar require react/promise:^2 # downgrade Promise for HHVM
+        uses: docker://hhvm/hhvm:3.30-lts-latest
         with:
-          version: lts-3.30
-      - run: composer self-update --2.2 # downgrade Composer for HHVM
-      - run: hhvm $(which composer) install
-      - run: hhvm vendor/phpunit/phpunit/phpunit
+          args: hhvm composer.phar require react/promise:^2
+      - name: Run hhvm vendor/bin/phpunit
+        uses: docker://hhvm/hhvm:3.30-lts-latest
+        with:
+          args: hhvm vendor/bin/phpunit
diff --git a/composer.json b/composer.json
index 01075a9..ff12bd5 100644
--- a/composer.json
+++ b/composer.json
@@ -10,12 +10,6 @@
             "email": "christian@clue.engineering"
         }
     ],
-    "autoload": {
-        "psr-4": { "ConnectionManager\\Extra\\": "src" }
-    },
-    "autoload-dev": {
-        "psr-4": { "ConnectionManager\\Tests\\Extra\\": "tests/" }
-    },
     "require": {
         "php": ">=5.3",
         "react/event-loop": "^1.2",
@@ -24,6 +18,16 @@
         "react/socket": "^1.12"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.3 || ^5.7 || ^4.8"
+        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36"
+    },
+    "autoload": {
+        "psr-4": {
+            "ConnectionManager\\Extra\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "ConnectionManager\\Tests\\Extra\\": "tests/"
+        }
     }
 }
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index b535d50..c5d22da 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<!-- PHPUnit configuration file with new format for PHPUnit 9.3+ -->
-<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
-         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+<!-- PHPUnit configuration file with new format for PHPUnit 9.6+ -->
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
          bootstrap="vendor/autoload.php"
          cacheResult="false"
          colors="true"
diff --git a/phpunit.xml.legacy b/phpunit.xml.legacy
index 36c0a9b..6531277 100644
--- a/phpunit.xml.legacy
+++ b/phpunit.xml.legacy
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<!-- PHPUnit configuration file with old format for PHPUnit 9.2 or older -->
+<!-- PHPUnit configuration file with old format for legacy PHPUnit -->
 <phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/4.8/phpunit.xsd"
          bootstrap="vendor/autoload.php"
@@ -15,4 +15,7 @@
             <directory>./src/</directory>
         </whitelist>
     </filter>
+    <php>
+        <ini name="error_reporting" value="-1" />
+    </php>
 </phpunit>