diff --git a/src/Symfony/Component/Form/FormRenderer.php b/src/Symfony/Component/Form/FormRenderer.php
index 100f478920..2f8f351990 100644
--- a/src/Symfony/Component/Form/FormRenderer.php
+++ b/src/Symfony/Component/Form/FormRenderer.php
@@ -59,7 +59,7 @@ class FormRenderer implements FormRendererInterface
     public function renderCsrfToken(string $tokenId)
     {
         if (null === $this->csrfTokenManager) {
-            throw new BadMethodCallException('CSRF tokens can only be generated if a CsrfTokenManagerInterface is injected in FormRenderer::__construct().');
+            throw new BadMethodCallException('CSRF tokens can only be generated if a CsrfTokenManagerInterface is injected in FormRenderer::__construct(). Try running "composer require symfony/security-csrf".');
         }
 
         return $this->csrfTokenManager->getToken($tokenId)->getValue();
diff --git a/src/Symfony/Component/HttpClient/Response/MockResponse.php b/src/Symfony/Component/HttpClient/Response/MockResponse.php
index 1d399d6625..bdb6559266 100644
--- a/src/Symfony/Component/HttpClient/Response/MockResponse.php
+++ b/src/Symfony/Component/HttpClient/Response/MockResponse.php
@@ -232,8 +232,8 @@ class MockResponse implements ResponseInterface, StreamableInterface
             $response->info['size_upload'] = 0.0;
         }
 
-        // simulate "total_time" if it is set
-        if (isset($response->info['total_time'])) {
+        // simulate "total_time" if it is not set
+        if (!isset($response->info['total_time'])) {
             $response->info['total_time'] = microtime(true) - $response->info['start_time'];
         }
 
@@ -281,7 +281,7 @@ class MockResponse implements ResponseInterface, StreamableInterface
             'http_code' => $response->info['http_code'],
         ] + $info + $response->info;
 
-        if (isset($response->info['total_time'])) {
+        if (!isset($response->info['total_time'])) {
             $response->info['total_time'] = microtime(true) - $response->info['start_time'];
         }
 
@@ -308,7 +308,7 @@ class MockResponse implements ResponseInterface, StreamableInterface
             $offset = \strlen($body);
         }
 
-        if (isset($response->info['total_time'])) {
+        if (!isset($response->info['total_time'])) {
             $response->info['total_time'] = microtime(true) - $response->info['start_time'];
         }
 
diff --git a/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php b/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
index 2ad9a1c379..def2c6f0ca 100644
--- a/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
+++ b/src/Symfony/Component/HttpClient/Tests/Response/MockResponseTest.php
@@ -11,6 +11,24 @@ use Symfony\Component\HttpClient\Response\MockResponse;
  */
 class MockResponseTest extends TestCase
 {
+    public function testTotalTimeShouldBeSimulatedWhenNotProvided()
+    {
+        $response = new MockResponse('body');
+        $response = MockResponse::fromRequest('GET', 'https://example.com/file.txt', [], $response);
+
+        $this->assertNotNull($response->getInfo('total_time'));
+        $this->assertGreaterThan(0.0, $response->getInfo('total_time'));
+    }
+
+    public function testTotalTimeShouldNotBeSimulatedWhenProvided()
+    {
+        $totalTime = 4.2;
+        $response = new MockResponse('body', ['total_time' => $totalTime]);
+        $response = MockResponse::fromRequest('GET', 'https://example.com/file.txt', [], $response);
+
+        $this->assertEquals($totalTime, $response->getInfo('total_time'));
+    }
+
     public function testToArray()
     {
         $data = ['color' => 'orange', 'size' => 42];