diff --git a/src/Symfony/Component/Cache/Adapter/RedisAdapter.php b/src/Symfony/Component/Cache/Adapter/RedisAdapter.php
index 922d3d3e5150..34f7c59926e3 100644
--- a/src/Symfony/Component/Cache/Adapter/RedisAdapter.php
+++ b/src/Symfony/Component/Cache/Adapter/RedisAdapter.php
@@ -90,6 +90,11 @@ public static function createConnection($dsn, array $options = array())
             $params['dbindex'] = $m[1];
             $params['path'] = substr($params['path'], 0, -strlen($m[0]));
         }
+        if (isset($params['host'])) {
+            $scheme = 'tcp';
+        } else {
+            $scheme = 'unix';
+        }
         $params += array(
             'host' => isset($params['host']) ? $params['host'] : $params['path'],
             'port' => isset($params['host']) ? 6379 : null,
@@ -120,7 +125,7 @@ public static function createConnection($dsn, array $options = array())
                 throw new InvalidArgumentException(sprintf('Redis connection failed (%s): %s', $e, $dsn));
             }
         } elseif (is_a($class, \Predis\Client::class, true)) {
-            $params['scheme'] = isset($params['host']) ? 'tcp' : 'unix';
+            $params['scheme'] = $scheme;
             $params['database'] = $params['dbindex'] ?: null;
             $params['password'] = $auth;
             $redis = new $class((new Factory())->create($params));