diff --git a/composer.json b/composer.json
index 0416b58..a43a6b3 100644
--- a/composer.json
+++ b/composer.json
@@ -27,7 +27,7 @@
     },
     "require": {
         "php": ">=5.4.2",
-        "guzzlehttp/psr7": "^1.0"
+        "guzzlehttp/psr7": "^1.7|^2.0"
     },
     "require-dev": {
         "phpunit/phpunit": "5.7.*",
diff --git a/tests/ab/clientRunner.php b/tests/ab/clientRunner.php
index 8dd964b..a4b9721 100644
--- a/tests/ab/clientRunner.php
+++ b/tests/ab/clientRunner.php
@@ -1,4 +1,6 @@
 <?php
+
+use GuzzleHttp\Psr7\Message;
 use GuzzleHttp\Psr7\Uri;
 use Ratchet\RFC6455\Handshake\InvalidPermessageDeflateOptionsException;
 use Ratchet\RFC6455\Handshake\PermessageDeflateOptions;
@@ -72,7 +74,7 @@ function getTestCases() {
                 if ($pos) {
                     $data = substr($rawResponse, $pos + 4);
                     $rawResponse = substr($rawResponse, 0, $pos + 4);
-                    $response = \GuzzleHttp\Psr7\parse_response($rawResponse);
+                    $response = Message::parseResponse($rawResponse);
 
                     if (!$cn->validateResponse($cnRequest, $response)) {
                         $connection->end();
@@ -101,7 +103,7 @@ function getTestCases() {
             }
         });
 
-        $connection->write(\GuzzleHttp\Psr7\str($cnRequest));
+        $connection->write(Message::toString($cnRequest));
     });
 
     return $deferred->promise();
@@ -137,7 +139,7 @@ function runTest($case)
                 if ($pos) {
                     $data = substr($rawResponse, $pos + 4);
                     $rawResponse = substr($rawResponse, 0, $pos + 4);
-                    $response = \GuzzleHttp\Psr7\parse_response($rawResponse);
+                    $response = Message::parseResponse($rawResponse);
 
                     if (!$cn->validateResponse($cnRequest, $response)) {
                         echo "Invalid response.\n";
@@ -167,7 +169,7 @@ function runTest($case)
             $deferred->resolve();
         });
 
-        $connection->write(\GuzzleHttp\Psr7\str($cnRequest));
+        $connection->write(Message::toString($cnRequest));
     });
 
     return $deferred->promise();
@@ -199,7 +201,7 @@ function createReport() {
                 if ($pos) {
                     $data = substr($rawResponse, $pos + 4);
                     $rawResponse = substr($rawResponse, 0, $pos + 4);
-                    $response = \GuzzleHttp\Psr7\parse_response($rawResponse);
+                    $response = Message::parseResponse($rawResponse);
 
                     if (!$cn->validateResponse($cnRequest, $response)) {
                         $connection->end();
@@ -228,7 +230,7 @@ function createReport() {
             }
         });
 
-        $connection->write(\GuzzleHttp\Psr7\str($cnRequest));
+        $connection->write(Message::toString($cnRequest));
     });
 
     return $deferred->promise();
diff --git a/tests/ab/startServer.php b/tests/ab/startServer.php
index f1d3b66..7c169c6 100644
--- a/tests/ab/startServer.php
+++ b/tests/ab/startServer.php
@@ -1,5 +1,6 @@
 <?php
 
+use GuzzleHttp\Psr7\Message;
 use GuzzleHttp\Psr7\Response;
 use Ratchet\RFC6455\Handshake\PermessageDeflateOptions;
 use Ratchet\RFC6455\Messaging\MessageBuffer;
@@ -35,18 +36,18 @@ $socket->on('connection', function (React\Socket\ConnectionInterface $connection
             return;
         }
         $headerComplete = true;
-        $psrRequest = \GuzzleHttp\Psr7\parse_request($parts[0] . "\r\n\r\n");
+        $psrRequest = Message::parseRequest($parts[0] . "\r\n\r\n");
         $negotiatorResponse = $negotiator->handshake($psrRequest);
 
         $negotiatorResponse = $negotiatorResponse->withAddedHeader("Content-Length", "0");
 
         if ($negotiatorResponse->getStatusCode() !== 101 && $psrRequest->getUri()->getPath() === '/shutdown') {
-            $connection->end(\GuzzleHttp\Psr7\str(new Response(200, [], 'Shutting down echo server.' . PHP_EOL)));
+            $connection->end(Message::toString(new Response(200, [], 'Shutting down echo server.' . PHP_EOL)));
             $socket->close();
             return;
         };
 
-        $connection->write(\GuzzleHttp\Psr7\str($negotiatorResponse));
+        $connection->write(Message::toString($negotiatorResponse));
 
         if ($negotiatorResponse->getStatusCode() !== 101) {
             $connection->end();
diff --git a/tests/unit/Handshake/ServerNegotiatorTest.php b/tests/unit/Handshake/ServerNegotiatorTest.php
index c08b9f3..720bdf9 100644
--- a/tests/unit/Handshake/ServerNegotiatorTest.php
+++ b/tests/unit/Handshake/ServerNegotiatorTest.php
@@ -2,6 +2,7 @@
 
 namespace Ratchet\RFC6455\Test\Unit\Handshake;
 
+use GuzzleHttp\Psr7\Message;
 use Ratchet\RFC6455\Handshake\RequestVerifier;
 use Ratchet\RFC6455\Handshake\ServerNegotiator;
 use PHPUnit\Framework\TestCase;
@@ -24,7 +25,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -53,7 +54,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -80,7 +81,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -107,7 +108,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -141,7 +142,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -175,7 +176,7 @@ Accept-Language: en-US,en;q=0.8
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);
 
@@ -205,7 +206,7 @@ Sec-WebSocket-Extensions: permessage-deflate; client_max_window_bits
 
 ';
 
-        $request = \GuzzleHttp\Psr7\parse_request($requestText);
+        $request = Message::parseRequest($requestText);
 
         $response = $negotiator->handshake($request);