diff --git a/composer.json b/composer.json
index 3b419ce..3d0eefa 100644
--- a/composer.json
+++ b/composer.json
@@ -10,16 +10,17 @@
     ],
     "require": {
         "php": "^7.1",
-        "nyholm/psr7": "^1.0",
+        "nyholm/psr7": "^1.3",
         "php-http/httplug": "^2.0",
         "psr/http-client": "^1.0",
-        "symfony/options-resolver": "^2.6 || ^3.0 || ^4.0 || ^5.0"
+        "symfony/options-resolver": "^2.6 || ^3.4 || ^4.4 || ^5.0"
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^2.2",
-        "php-http/client-integration-tests": "dev-master",
-        "php-http/message": "^1.0",
-        "php-http/client-common": "^2.0"
+        "php-http/client-integration-tests": "^3.0",
+        "php-http/message": "^1.9",
+        "php-http/client-common": "^2.3",
+        "phpunit/phpunit": "^8.5.8"
     },
     "provide": {
         "php-http/client-implementation": "1.0",
diff --git a/tests/BaseTestCase.php b/tests/BaseTestCase.php
index a6ffda7..43d26a6 100644
--- a/tests/BaseTestCase.php
+++ b/tests/BaseTestCase.php
@@ -28,7 +28,7 @@ public function stopServer($name)
         }
     }
 
-    public function tearDown()
+    public function tearDown(): void
     {
         foreach (array_keys($this->servers) as $name) {
             $this->stopServer($name);