diff --git a/src/redis/src/RedisConnection.php b/src/redis/src/RedisConnection.php
index 1cef7a3bb..7cb3b3ef6 100644
--- a/src/redis/src/RedisConnection.php
+++ b/src/redis/src/RedisConnection.php
@@ -37,7 +37,7 @@ class RedisConnection extends BaseConnection implements ConnectionInterface
     ];
 
     /**
-     * Current database.
+     * Current redis database.
      * @var null|int
      */
     protected $database;
@@ -111,7 +111,7 @@ class RedisConnection extends BaseConnection implements ConnectionInterface
         parent::release();
     }
 
-    public function setDatabase($database): void
+    public function setDatabase(?int $database): void
     {
         $this->database = $database;
     }
diff --git a/src/redis/tests/Stub/RedisConnectionStub.php b/src/redis/tests/Stub/RedisConnectionStub.php
index b0964b3d4..502bf43da 100644
--- a/src/redis/tests/Stub/RedisConnectionStub.php
+++ b/src/redis/tests/Stub/RedisConnectionStub.php
@@ -58,7 +58,7 @@ class RedisConnectionStub extends RedisConnection
     /**
      * @return null|int
      */
-    public function getDatabase()
+    public function getDatabase(): ?int
     {
         return $this->database;
     }