diff --git a/.travis.yml b/.travis.yml
index 6af5f34..0c9a55f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,9 +1,6 @@
 language: php
-
 sudo: false
 
-dist: trusty
-
 cache:
     directories:
         - $HOME/.composer/cache/files
@@ -19,17 +16,15 @@ branches:
 matrix:
     fast_finish: true
     include:
-        - php: 7.1
-          env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest" DEPENDENCIES="doctrine/instantiator:^1.1"
+        - php: 7.0
+          env: COMPOSER_FLAGS="--prefer-stable --prefer-lowest"
 
           # 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"
+        - php: 7.2
+          env: COVERAGE=true TEST_COMMAND="composer test-ci"  DEPENDENCIES="leanphp/phpspec-code-coverage"
 
           # Test LTS versions
         - php: 7.1
@@ -44,9 +39,10 @@ matrix:
           env: STABILITY="dev"
 
     allow_failures:
-          # Latest dev is allowed to fail.
+        - php: 7.3
+          sudo: required
         - env: STABILITY="dev"
-          
+
 before_install:
     - if [[ $COVERAGE != true ]]; then phpenv config-rm xdebug.ini || true; fi
     - if ! [ -z "$STABILITY" ]; then composer config minimum-stability ${STABILITY}; fi;
diff --git a/composer.json b/composer.json
index 4695c4c..fc3d1c1 100644
--- a/composer.json
+++ b/composer.json
@@ -11,15 +11,18 @@
         }
     ],
     "require": {
-        "php": "^5.4 || ^7.0",
-        "php-http/httplug": "^1.1",
+        "php": "^7.0",
+        "php-http/httplug": "^2.0",
         "php-http/message-factory": "^1.0",
         "php-http/message": "^1.6",
         "symfony/options-resolver": "^2.6 || ^3.0 || ^4.0"
     },
     "require-dev": {
-        "phpspec/phpspec": "^2.5 || ^3.4 || ^4.2",
-        "guzzlehttp/psr7": "^1.4"
+        "doctrine/instantiator": ">=1.0.5",
+        "guzzlehttp/psr7": "^1.4",
+        "phpspec/phpspec": "^3.4 || ^4.2",
+        "phpspec/prophecy": ">=1.8",
+        "sebastian/comparator": ">=2"
     },
     "suggest": {
         "php-http/logger-plugin": "PSR-3 Logger plugin",
@@ -37,6 +40,7 @@
     },
     "extra": {
         "branch-alias": {
+            "dev-2.x": "2.x-dev",
             "dev-master": "1.8-dev"
         }
     }
diff --git a/phpspec.ci.yml b/phpspec.ci.yml
index 0838ef5..d8e1383 100644
--- a/phpspec.ci.yml
+++ b/phpspec.ci.yml
@@ -4,7 +4,7 @@ suites:
         psr4_prefix: Http\Client\Common
 formatter.name: pretty
 extensions:
-    - PhpSpec\Extension\CodeCoverageExtension
+    LeanPHP\PhpSpec\CodeCoverage\CodeCoverageExtension: ~
 code_coverage:
     format: clover
     output: build/coverage.xml
diff --git a/spec/HttpClientPool/LeastUsedClientPoolSpec.php b/spec/HttpClientPool/LeastUsedClientPoolSpec.php
index a976c31..82855d9 100644
--- a/spec/HttpClientPool/LeastUsedClientPoolSpec.php
+++ b/spec/HttpClientPool/LeastUsedClientPoolSpec.php
@@ -72,10 +72,6 @@ public function it_reenable_client(HttpClient $client, RequestInterface $request
 
     public function it_uses_the_lowest_request_client(HttpClientPoolItem $client1, HttpClientPoolItem $client2, RequestInterface $request, ResponseInterface $response)
     {
-        if (extension_loaded('xdebug')) {
-            throw new SkippingException('This test fail when xdebug is enable on PHP < 7');
-        }
-
         $this->addHttpClient($client1);
         $this->addHttpClient($client2);
 
diff --git a/src/BatchClient.php b/src/BatchClient.php
index 2036355..2a39904 100644
--- a/src/BatchClient.php
+++ b/src/BatchClient.php
@@ -6,6 +6,7 @@
 use Http\Client\HttpClient;
 use Http\Client\Common\Exception\BatchException;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * BatchClient allow to sends multiple request and retrieve a Batch Result.
@@ -32,7 +33,7 @@ public function __construct(HttpClient $client)
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         return $this->client->sendRequest($request);
     }
diff --git a/src/HttpAsyncClientEmulator.php b/src/HttpAsyncClientEmulator.php
index c0ba354..ce16f84 100644
--- a/src/HttpAsyncClientEmulator.php
+++ b/src/HttpAsyncClientEmulator.php
@@ -5,6 +5,7 @@
 use Http\Client\Exception;
 use Http\Client\Promise;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Emulates an HTTP Async Client in an HTTP Client.
@@ -18,7 +19,7 @@ trait HttpAsyncClientEmulator
      *
      * @see HttpClient::sendRequest
      */
-    abstract public function sendRequest(RequestInterface $request);
+    abstract public function sendRequest(RequestInterface $request): ResponseInterface;
 
     /**
      * {@inheritdoc}
diff --git a/src/HttpClientDecorator.php b/src/HttpClientDecorator.php
index a33d5ef..da5a1bb 100644
--- a/src/HttpClientDecorator.php
+++ b/src/HttpClientDecorator.php
@@ -4,6 +4,7 @@
 
 use Http\Client\HttpClient;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Decorates an HTTP Client.
@@ -22,7 +23,7 @@ trait HttpClientDecorator
      *
      * @see HttpClient::sendRequest
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         return $this->httpClient->sendRequest($request);
     }
diff --git a/src/HttpClientEmulator.php b/src/HttpClientEmulator.php
index dbec1ab..8e6472a 100644
--- a/src/HttpClientEmulator.php
+++ b/src/HttpClientEmulator.php
@@ -3,6 +3,7 @@
 namespace Http\Client\Common;
 
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Emulates an HTTP Client in an HTTP Async Client.
@@ -16,7 +17,7 @@ trait HttpClientEmulator
      *
      * @see HttpClient::sendRequest
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         $promise = $this->sendAsyncRequest($request);
 
diff --git a/src/HttpClientPool.php b/src/HttpClientPool.php
index 7ac292c..6f4597f 100644
--- a/src/HttpClientPool.php
+++ b/src/HttpClientPool.php
@@ -6,6 +6,7 @@
 use Http\Client\HttpAsyncClient;
 use Http\Client\HttpClient;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * A http client pool allows to send requests on a pool of different http client using a specific strategy (least used,
@@ -52,7 +53,7 @@ public function sendAsyncRequest(RequestInterface $request)
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         return $this->chooseHttpClient()->sendRequest($request);
     }
diff --git a/src/HttpClientPoolItem.php b/src/HttpClientPoolItem.php
index 09cd6dd..a46ee2f 100644
--- a/src/HttpClientPoolItem.php
+++ b/src/HttpClientPoolItem.php
@@ -6,6 +6,7 @@
 use Http\Client\HttpClient;
 use Psr\Http\Message\RequestInterface;
 use Http\Client\Exception;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * A HttpClientPoolItem represent a HttpClient inside a Pool.
@@ -50,7 +51,7 @@ public function __construct($client, $reenableAfter = null)
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         if ($this->isDisabled()) {
             throw new Exception\RequestException('Cannot send the request as this client has been disabled', $request);
diff --git a/src/HttpClientRouter.php b/src/HttpClientRouter.php
index 9f72133..fa32c56 100644
--- a/src/HttpClientRouter.php
+++ b/src/HttpClientRouter.php
@@ -7,6 +7,7 @@
 use Http\Client\HttpClient;
 use Http\Message\RequestMatcher;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 
 /**
  * Route a request to a specific client in the stack based using a RequestMatcher.
@@ -23,7 +24,7 @@ final class HttpClientRouter implements HttpClient, HttpAsyncClient
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         $client = $this->chooseHttpClient($request);
 
diff --git a/src/HttpMethodsClient.php b/src/HttpMethodsClient.php
index 58804fc..0ec1e14 100644
--- a/src/HttpMethodsClient.php
+++ b/src/HttpMethodsClient.php
@@ -198,7 +198,7 @@ public function send($method, $uri, array $headers = [], $body = null)
      *
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         return $this->httpClient->sendRequest($request);
     }
diff --git a/src/PluginClient.php b/src/PluginClient.php
index 93aea8f..7413152 100644
--- a/src/PluginClient.php
+++ b/src/PluginClient.php
@@ -9,6 +9,7 @@
 use Http\Client\Promise\HttpFulfilledPromise;
 use Http\Client\Promise\HttpRejectedPromise;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\ResponseInterface;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 
 /**
@@ -67,7 +68,7 @@ public function __construct($client, array $plugins = [], array $options = [])
     /**
      * {@inheritdoc}
      */
-    public function sendRequest(RequestInterface $request)
+    public function sendRequest(RequestInterface $request): ResponseInterface
     {
         // If we don't have an http client, use the async call
         if (!($this->client instanceof HttpClient)) {