diff --git a/examples/public/client_credentials.php b/examples/public/client_credentials.php
index ca43fafb..1e671d3a 100644
--- a/examples/public/client_credentials.php
+++ b/examples/public/client_credentials.php
@@ -32,9 +32,9 @@ $app->post('/access_token', function (Request $request, Response $response) {
     /** @var Server $server */
     $server = $this->get(Server::class);
     try {
-        return $server->respondToRequest($request);
+        return $server->respondToRequest($request, $response);
     } catch (OAuthServerException $e) {
-        return $e->generateHttpResponse();
+        return $e->generateHttpResponse($response);
     } catch (\Exception $e) {
         return $response->withStatus(500)->write($e->getMessage());
     }
diff --git a/examples/public/password.php b/examples/public/password.php
index d9ff5f8b..de73d63d 100644
--- a/examples/public/password.php
+++ b/examples/public/password.php
@@ -43,9 +43,9 @@ $app->post('/access_token', function (Request $request, Response $response) {
     /** @var Server $server */
     $server = $this->get(Server::class);
     try {
-        return $server->respondToRequest($request);
+        return $server->respondToRequest($request, $response);
     } catch (OAuthServerException $e) {
-        return $e->generateHttpResponse();
+        return $e->generateHttpResponse($response);
     } catch (\Exception $e) {
         return $response->withStatus(500)->write($e->getMessage());
     }
diff --git a/examples/public/refresh_token.php b/examples/public/refresh_token.php
index 75c08139..d41e940b 100644
--- a/examples/public/refresh_token.php
+++ b/examples/public/refresh_token.php
@@ -43,9 +43,9 @@ $app->post('/access_token', function (Request $request, Response $response) {
     /** @var Server $server */
     $server = $this->get(Server::class);
     try {
-        return $server->respondToRequest($request);
+        return $server->respondToRequest($request, $response);
     } catch (OAuthServerException $e) {
-        return $e->generateHttpResponse();
+        return $e->generateHttpResponse($response);
     } catch (\Exception $e) {
         return $response->withStatus(500)->write(
             sprintf('<h1>%s</h1><p>%s</p>', get_class($e), $e->getMessage())
diff --git a/src/Exception/OAuthServerException.php b/src/Exception/OAuthServerException.php
index 28c9b799..f97e3b5a 100644
--- a/src/Exception/OAuthServerException.php
+++ b/src/Exception/OAuthServerException.php
@@ -204,8 +204,12 @@ class OAuthServerException extends \Exception
      *
      * @return ResponseInterface
      */
-    public function generateHttpResponse()
+    public function generateHttpResponse(ResponseInterface $response = null)
     {
+        if (!$response instanceof ResponseInterface) {
+            $response = new Response();
+        }
+
         $headers = $this->getHttpHeaders();
 
         $payload = [
@@ -221,12 +225,13 @@ class OAuthServerException extends \Exception
             $headers['Location'] = RedirectUri::make($this->redirectUri, $payload);
         }
 
-        $response = new Response(
-            'php://memory',
-            $this->getHttpStatusCode(),
-            $headers
-        );
-        $response->getBody()->write(json_encode($payload));
+        foreach ($headers as $header => $content) {
+            $response->withHeader($header, $content);
+        }
+
+        $response
+            ->withStatus($this->getHttpStatusCode())
+            ->getBody()->write(json_encode($payload));
 
         return $response;
     }
@@ -254,8 +259,7 @@ class OAuthServerException extends \Exception
         if ($this->errorType === 'invalid_client') {
             $authScheme = null;
             $request = new ServerRequest();
-            if (
-                isset($request->getServerParams()['PHP_AUTH_USER']) &&
+            if (isset($request->getServerParams()['PHP_AUTH_USER']) &&
                 $request->getServerParams()['PHP_AUTH_USER'] !== null
             ) {
                 $authScheme = 'Basic';
diff --git a/src/ResponseTypes/BearerTokenResponse.php b/src/ResponseTypes/BearerTokenResponse.php
index 85b5c235..2397286e 100644
--- a/src/ResponseTypes/BearerTokenResponse.php
+++ b/src/ResponseTypes/BearerTokenResponse.php
@@ -16,6 +16,7 @@ use Lcobucci\JWT\Signer\Key;
 use Lcobucci\JWT\Signer\Rsa\Sha256;
 use League\OAuth2\Server\Entities\Interfaces\RefreshTokenEntityInterface;
 use League\OAuth2\Server\Utils\KeyCrypt;
+use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
 use Zend\Diactoros\Response;
 
@@ -24,7 +25,7 @@ class BearerTokenResponse extends AbstractResponseType
     /**
      * {@inheritdoc}
      */
-    public function generateHttpResponse()
+    public function generateHttpResponse(ResponseInterface $response)
     {
         $jwtAccessToken = (new Builder())
             ->setAudience($this->accessToken->getClient()->getIdentifier())
@@ -61,16 +62,12 @@ class BearerTokenResponse extends AbstractResponseType
             $responseParams['refresh_token'] = $refreshToken;
         }
 
-        $response = new Response(
-            'php://memory',
-            200,
-            [
-                'pragma'        => 'no-cache',
-                'cache-control' => 'no-store',
-                'content-type'  => 'application/json;charset=UTF-8'
-            ]
-        );
-        $response->getBody()->write(json_encode($responseParams));
+        $response
+            ->withStatus(200)
+            ->withHeader('pragma', 'no-cache')
+            ->withHeader('cache-control', 'no-store')
+            ->withHeader('content-type', 'application/json;charset=UTF-8')
+            ->getBody()->write(json_encode($responseParams));
 
         return $response;
     }
diff --git a/src/ResponseTypes/ResponseTypeInterface.php b/src/ResponseTypes/ResponseTypeInterface.php
index fef9cb59..00c3ed14 100644
--- a/src/ResponseTypes/ResponseTypeInterface.php
+++ b/src/ResponseTypes/ResponseTypeInterface.php
@@ -38,7 +38,9 @@ interface ResponseTypeInterface
     public function determineAccessTokenInHeader(ServerRequestInterface $request);
 
     /**
+     * @param ResponseInterface $response
+     *
      * @return ResponseInterface
      */
-    public function generateHttpResponse();
+    public function generateHttpResponse(ResponseInterface $response);
 }
diff --git a/src/Server.php b/src/Server.php
index b18bddf4..cd7e6e46 100644
--- a/src/Server.php
+++ b/src/Server.php
@@ -9,7 +9,9 @@ use League\OAuth2\Server\Exception\OAuthServerException;
 use League\OAuth2\Server\Grant\GrantTypeInterface;
 use League\OAuth2\Server\ResponseTypes\BearerTokenResponse;
 use League\OAuth2\Server\ResponseTypes\ResponseTypeInterface;
+use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
+use Zend\Diactoros\Response;
 use Zend\Diactoros\ServerRequestFactory;
 
 class Server implements EmitterAwareInterface
@@ -121,16 +123,21 @@ class Server implements EmitterAwareInterface
      * Return an access token response
      *
      * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param \Psr\Http\Message\ResponseInterface      $response
      *
-     * @return \League\OAuth2\Server\ResponseTypes\ResponseTypeInterface
+     * @return \Psr\Http\Message\ResponseInterface
      * @throws \League\OAuth2\Server\Exception\OAuthServerException
      */
-    public function respondToRequest(ServerRequestInterface $request = null)
+    public function respondToRequest(ServerRequestInterface $request = null, ResponseInterface $response = null)
     {
-        if ($request === null) {
+        if (!$request instanceof ServerRequestInterface) {
             $request = ServerRequestFactory::fromGlobals();
         }
 
+        if (!$response instanceof ResponseInterface) {
+            $response = new Response();
+        }
+
         $tokenResponse = null;
         foreach ($this->enabledGrantTypes as $grantType) {
             if ($grantType->canRespondToRequest($request)) {
@@ -143,12 +150,30 @@ class Server implements EmitterAwareInterface
             }
         }
 
-        if ($tokenResponse instanceof ResponseTypeInterface) {
-            return $tokenResponse->generateHttpResponse();
-        } else {
-            $response = OAuthServerException::unsupportedGrantType()->generateHttpResponse();
+        if (!$tokenResponse instanceof ResponseTypeInterface) {
+            return OAuthServerException::unsupportedGrantType()->generateHttpResponse($response);
         }
 
-        return $response;
+        return $tokenResponse->generateHttpResponse($response);
+    }
+
+    /**
+     * PSR7 middleware callable
+     *
+     * @param \Psr\Http\Message\ServerRequestInterface $request
+     * @param \Psr\Http\Message\ResponseInterface      $response
+     *
+     * @return \Psr\Http\Message\ResponseInterface
+     * @throws \League\OAuth2\Server\Exception\OAuthServerException
+     */
+    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $next)
+    {
+        $response = $this->respondToRequest($request, $response);
+
+        if (in_array($response->getStatusCode(), [400, 401, 500])) {
+            return $response;
+        }
+
+        return $next($request, $response);
     }
 }