diff --git a/src/Symfony/Component/Notifier/Test/TransportTestCase.php b/src/Symfony/Component/Notifier/Test/TransportTestCase.php
index d81e8b79c05c6..012f4c56fa73d 100644
--- a/src/Symfony/Component/Notifier/Test/TransportTestCase.php
+++ b/src/Symfony/Component/Notifier/Test/TransportTestCase.php
@@ -96,7 +96,7 @@ public function testCanSetCustomHost()
 
         $transport->setHost($customHost = self::CUSTOM_HOST);
 
-        $this->assertStringContainsString(sprintf('://%s', $customHost), (string) $transport);
+        $this->assertMatchesRegularExpression(sprintf('/^.*\:\/\/(%s|.*\@%s)/', $customHost, $customHost), (string) $transport);
     }
 
     public function testCanSetCustomPort()
@@ -106,9 +106,9 @@ public function testCanSetCustomPort()
         $transport->setPort($customPort = self::CUSTOM_PORT);
 
         /*
-         * @see https://regex101.com/r/0xQKuY/2
+         * @see https://regex101.com/r/shT9O2/1
          */
-        $this->assertMatchesRegularExpression(sprintf('/^.*\/\/.*\:%s.*$/', $customPort), (string) $transport);
+        $this->assertMatchesRegularExpression(sprintf('/^.*\:\/\/.*(\@.*)?\:%s((\?.*|\/.*))?$/', $customPort), (string) $transport);
     }
 
     public function testCanSetCustomHostAndPort()
@@ -118,6 +118,6 @@ public function testCanSetCustomHostAndPort()
         $transport->setHost($customHost = self::CUSTOM_HOST);
         $transport->setPort($customPort = self::CUSTOM_PORT);
 
-        $this->assertStringContainsString(sprintf('://%s:%s', $customHost, $customPort), (string) $transport);
+        $this->assertMatchesRegularExpression(sprintf('/^.*\:\/\/(%s|.*\@%s)\:%s/', $customHost, $customHost, $customPort), (string) $transport);
     }
 }