diff --git a/composer.json b/composer.json
index 3fd0fb4..c4c424c 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
     "guzzlehttp/guzzle": "^6.3 || ^7.0",
     "softonic/guzzle-oauth2-middleware": "^2.1",
     "ext-json": "*",
-    "symfony/console": "^5.0 || ^6.0 || ^7.0"
+    "symfony/console": "^6.0 || ^7.0"
   },
   "require-dev": {
     "friendsofphp/php-cs-fixer": "^3.9",
diff --git a/src/Console/Mutation/GenerateConfig.php b/src/Console/Mutation/GenerateConfig.php
index 03cdfcc..330d14c 100644
--- a/src/Console/Mutation/GenerateConfig.php
+++ b/src/Console/Mutation/GenerateConfig.php
@@ -54,7 +54,7 @@ protected function configure()
             );
     }
 
-    protected function execute(InputInterface $input, OutputInterface $output)
+    protected function execute(InputInterface $input, OutputInterface $output): int
     {
         if (!$this->checkArguments($input, $output)) {
             return 1;
diff --git a/tests/ResponseBuilderTest.php b/tests/ResponseBuilderTest.php
index 49944cb..d7e3c8a 100644
--- a/tests/ResponseBuilderTest.php
+++ b/tests/ResponseBuilderTest.php
@@ -2,8 +2,10 @@
 
 namespace Softonic\GraphQL;
 
+use GuzzleHttp\Psr7\BufferStream;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\StreamInterface;
 use UnexpectedValueException;
 
 class ResponseBuilderTest extends TestCase
@@ -24,7 +26,7 @@ public function testBuildMalformedResponse()
         $mockHttpResponse = $this->createMock(ResponseInterface::class);
         $mockHttpResponse->expects($this->once())
             ->method('getBody')
-            ->willReturn('malformed response');
+            ->willReturn($this->stringToStream('malformed response'));
 
         $this->expectException(UnexpectedValueException::class);
         $this->expectExceptionMessage('Invalid JSON response. Response body: ');
@@ -53,7 +55,7 @@ public function testBuildInvalidGraphqlJsonResponse(string $body)
 
         $mockHttpResponse->expects($this->once())
             ->method('getBody')
-            ->willReturn($body);
+            ->willReturn($this->stringToStream($body));
 
         $this->expectException(UnexpectedValueException::class);
         $this->expectExceptionMessage('Invalid GraphQL JSON response. Response body: ');
@@ -67,7 +69,7 @@ public function testBuildValidGraphqlJsonWithoutErrors()
 
         $mockHttpResponse->expects($this->once())
             ->method('getBody')
-            ->willReturn('{"data": {"foo": "bar"}}');
+            ->willReturn($this->stringToStream('{"data": {"foo": "bar"}}'));
 
         $expectedData   = ['foo' => 'bar'];
         $dataObjectMock = [
@@ -107,7 +109,7 @@ public function testBuildValidGraphqlJsonWithErrors(string $body)
 
         $mockHttpResponse->expects($this->once())
             ->method('getBody')
-            ->willReturn($body);
+            ->willReturn($this->stringToStream($body));
 
         $this->dataObjectBuilder->expects($this->once())
             ->method('buildQuery')
@@ -121,4 +123,13 @@ public function testBuildValidGraphqlJsonWithErrors(string $body)
         $this->assertTrue($response->hasErrors());
         $this->assertEquals([['foo' => 'bar']], $response->getErrors());
     }
+
+    public function stringToStream(string $string): StreamInterface
+    {
+        $buffer = new BufferStream();
+
+        $buffer->write($string);
+
+        return $buffer;
+    }
 }