diff --git a/.travis.yml b/.travis.yml
index 730574d..5acdf9a 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,11 +7,9 @@ env:
 matrix:
   fast_finish: true
   include:
-    - php: 7.0
-      dist: xenial
-      env: deps=low
     - php: 7.1
       dist: bionic
+      env: deps=low
     - php: 7.2
       dist: bionic
     - php: 7.3
diff --git a/README.md b/README.md
index 2397ed8..5b266bc 100644
--- a/README.md
+++ b/README.md
@@ -12,10 +12,14 @@ You can sign up for a Clearhaus account at https://www.clearhaus.com/.
 
 ## Requirements
 
-* PHP 7.0+
+* PHP 7.1+
 * [php-http/client-common ^1.3](https://github.com/php-http/client-common)
-* [php-http/discovery ^1.0](https://github.com/php-http/discovery)
+* [php-http/discovery ^1.6](https://github.com/php-http/discovery)
 * [php-http/httplug ^1.0](https://github.com/php-http/httplug)
+* [php-http/message-factory ^1.0.2](https://github.com/php-http/message-factory)
+* [phpseclib/phpseclib ^2.0](https://github.com/phpseclib/phpseclib)
+* [psr/container ^1.0](https://github.com/php-fig/container)
+* [psr/http-message ^1.0](https://github.com/php-fig/http-message)
 
 ## Installation
 
diff --git a/composer.json b/composer.json
index 9a1c8c4..f71c96b 100644
--- a/composer.json
+++ b/composer.json
@@ -25,7 +25,7 @@
     }
   },
   "require": {
-    "php": "^7.0",
+    "php": "^7.1",
     "php-http/client-common": "^1.3",
     "php-http/discovery": "^1.6",
     "php-http/httplug": "^1.0",
@@ -35,9 +35,10 @@
     "psr/http-message": "^1.0"
   },
   "require-dev": {
-    "phpspec/phpspec": "^4.0 || ^5.0 || ^6.0",
+    "phpspec/phpspec": "^5.0 || ^6.0",
     "phpspec/prophecy": "^1.6.2",
-    "laminas/laminas-diactoros": "^1.6 || ^2.0"
+    "guzzlehttp/psr7": "^1.6",
+    "http-interop/http-factory-guzzle": "^1.0"
   },
   "suggest": {
     "ext-openssl": "Allow to sign requests using RSA signature of the HTTP body."
diff --git a/spec/Api/AbstractSpec.php b/spec/Api/AbstractSpec.php
index 5e5c57b..4d07894 100644
--- a/spec/Api/AbstractSpec.php
+++ b/spec/Api/AbstractSpec.php
@@ -3,16 +3,15 @@
 namespace spec\Clearhaus\Api;
 
 use Clearhaus\Client;
+use GuzzleHttp\Psr7;
+use GuzzleHttp\Psr7\Response;
 use PhpSpec\ObjectBehavior;
-use Laminas\Diactoros\Response;
-use Laminas\Diactoros\Stream;
 
 abstract class AbstractSpec extends ObjectBehavior
 {
     protected function createHttpResponse(array $body) : Response
     {
-        $stream = new Stream('php://memory', 'rw');
-        $stream->write(json_encode($body, JSON_FORCE_OBJECT));
+        $stream = Psr7\stream_for(\json_encode($body, JSON_FORCE_OBJECT));
         $stream->rewind();
 
         $httpResponse = (new Response())
diff --git a/spec/ClientSpec.php b/spec/ClientSpec.php
index e3f6468..64d0a2a 100644
--- a/spec/ClientSpec.php
+++ b/spec/ClientSpec.php
@@ -26,7 +26,7 @@ function it_is_initializable()
 
     function it_should_enable_signature(Builder $builder)
     {
-        $builder->addPlugin(Argument::type(Plugin::class))->willReturn(null);
+        $builder->addPlugin(Argument::type(Plugin::class))->shouldBeCalled();
 
         $builder->addPlugin(Argument::type(SignaturePlugin::class))->shouldBeCalled();
 
@@ -35,7 +35,7 @@ function it_should_enable_signature(Builder $builder)
 
     function it_should_return_http_client(Builder $builder, HttpMethodsClient $httpMethodsClient)
     {
-        $builder->addPlugin(Argument::type(Plugin::class))->willReturn(null);
+        $builder->addPlugin(Argument::type(Plugin::class))->shouldBeCalled();
 
         $builder->build()->willReturn($httpMethodsClient);
 
diff --git a/spec/HttpClient/Plugin/ErrorPluginSpec.php b/spec/HttpClient/Plugin/ErrorPluginSpec.php
index 3272389..98f5cf4 100644
--- a/spec/HttpClient/Plugin/ErrorPluginSpec.php
+++ b/spec/HttpClient/Plugin/ErrorPluginSpec.php
@@ -9,13 +9,13 @@
 use Clearhaus\Exception\ValidationFailedException;
 use Clearhaus\HttpClient\Plugin\ErrorPlugin;
 use Exception;
+use GuzzleHttp\Psr7;
+use GuzzleHttp\Psr7\Response;
 use Http\Promise\FulfilledPromise;
 use Http\Promise\Promise;
 use Http\Promise\RejectedPromise;
 use PhpSpec\ObjectBehavior;
 use Psr\Http\Message\RequestInterface;
-use Laminas\Diactoros\Response;
-use Laminas\Diactoros\Stream;
 
 class ErrorPluginSpec extends ObjectBehavior
 {
@@ -120,8 +120,7 @@ private function createFailedHttpResponse(int $statusCode,int  $errorCode, strin
 
     private function createHttpResponse(array $body, int $statusCode = 200) : Response
     {
-        $stream = new Stream('php://memory', 'rw');
-        $stream->write(json_encode($body, JSON_FORCE_OBJECT));
+        $stream = Psr7\stream_for(\json_encode($body, JSON_FORCE_OBJECT));
         $stream->rewind();
 
         $httpResponse = (new Response())
diff --git a/src/Client.php b/src/Client.php
index ac39950..98d1b07 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -55,7 +55,7 @@ public function __construct(string $apiKey, Builder $builder = null, string $mod
         ));
     }
 
-    public function enableSignature()
+    public function enableSignature(): void
     {
         $encrypter = new RSA();
         $this->builder->addPlugin(new SignaturePlugin($encrypter, $this->apiKey));
diff --git a/src/HttpClient/Builder.php b/src/HttpClient/Builder.php
index d26f812..212c607 100644
--- a/src/HttpClient/Builder.php
+++ b/src/HttpClient/Builder.php
@@ -67,13 +67,13 @@ public function build() : HttpMethodsClient
         return $this->pluginClient;
     }
 
-    public function addPlugin(Plugin $plugin)
+    public function addPlugin(Plugin $plugin): void
     {
         $this->plugins[] = $plugin;
         $this->httpClientModified = true;
     }
 
-    public function removePlugin(string $fqcn)
+    public function removePlugin(string $fqcn): void
     {
         foreach ($this->plugins as $index => $plugin) {
             if ($plugin instanceof $fqcn) {