diff --git a/.travis.yml b/.travis.yml
index bf50516..21525cb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,23 +17,17 @@ matrix:
     fast_finish: true
     include:
           # Test with lowest dependencies
-        - php: 7.1
+        - php: 7.3
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak"
-        - php: 5.4
+        - php: 7.1
           env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" SYMFONY_DEPRECATIONS_HELPER="weak"
 
           # Test the latest stable release
-        - php: 5.4
-        - php: 5.5
-        - php: 5.6
-        - php: 7.0
         - php: 7.1
         - php: 7.2
           env: COVERAGE=true TEST_COMMAND="composer test-ci" DEPENDENCIES="henrikbjorn/phpspec-code-coverage:^1.0"
 
           # Force some major versions of Symfony
-        - php: 7.2
-          env: DEPENDENCIES="dunglas/symfony-lock:^2"
         - php: 7.2
           env: DEPENDENCIES="dunglas/symfony-lock:^3"
         - php: 7.2
diff --git a/composer.json b/composer.json
index 76424fb..388e748 100644
--- a/composer.json
+++ b/composer.json
@@ -11,12 +11,12 @@
         }
     ],
     "require": {
-        "php": ">=5.4",
-        "symfony/stopwatch": "^2.7|^3.0|^4.0",
-        "php-http/client-common": "^1.1"
+        "php": "^7.1",
+        "symfony/stopwatch": "^3.4 || ^4.0",
+        "php-http/client-common": "^2.0"
     },
     "require-dev": {
-        "phpspec/phpspec": "^2.5 || ^3.0 || ^4.0"
+        "phpspec/phpspec": "^4.0"
     },
     "autoload": {
         "psr-4": {
@@ -29,6 +29,7 @@
     },
     "extra": {
         "branch-alias": {
+            "dev-2.x": "2.x-dev",
             "dev-master": "1.0-dev"
         }
     },
diff --git a/src/StopwatchPlugin.php b/src/StopwatchPlugin.php
index 8e3054a..71e11c5 100644
--- a/src/StopwatchPlugin.php
+++ b/src/StopwatchPlugin.php
@@ -4,6 +4,7 @@
 
 use Http\Client\Common\Plugin;
 use Http\Client\Exception;
+use Http\Promise\Promise;
 use Psr\Http\Message\RequestInterface;
 use Psr\Http\Message\ResponseInterface;
 use Symfony\Component\Stopwatch\Stopwatch;
@@ -33,7 +34,7 @@ public function __construct(Stopwatch $stopwatch)
     /**
      * {@inheritdoc}
      */
-    public function handleRequest(RequestInterface $request, callable $next, callable $first)
+    public function handleRequest(RequestInterface $request, callable $next, callable $first): Promise
     {
         $eventName = $this->getStopwatchEventName($request);
         $this->stopwatch->start($eventName, self::CATEGORY);