diff --git a/src/Connection/Aggregate/SentinelReplication.php b/src/Connection/Aggregate/SentinelReplication.php
index 069f3a44..7ab04350 100644
--- a/src/Connection/Aggregate/SentinelReplication.php
+++ b/src/Connection/Aggregate/SentinelReplication.php
@@ -239,14 +239,13 @@ class SentinelReplication implements ReplicationInterface
         }
 
         if (is_array($parameters)) {
-            $parameters += array(
-                'timeout' => $this->sentinelTimeout,
+            // We unset "password" and "database" from user-supplied parameters
+            // as they are not needed when connecting to sentinels.
+            unset($parameters['database'], $parameters['password']);
 
-                // We need to override password and database by setting them to
-                // NULL as they are not needed when connecting to sentinels.
-                'password' => null,
-                'database' => null,
-            );
+            if (!isset($parameters['timeout'])) {
+                $parameters['timeout'] = $this->sentinelTimeout;
+            }
         }
 
         $connection = $this->connectionFactory->create($parameters);
diff --git a/tests/Predis/Connection/Aggregate/SentinelReplicationTest.php b/tests/Predis/Connection/Aggregate/SentinelReplicationTest.php
index b5b39eed..d4a5116c 100644
--- a/tests/Predis/Connection/Aggregate/SentinelReplicationTest.php
+++ b/tests/Predis/Connection/Aggregate/SentinelReplicationTest.php
@@ -33,6 +33,69 @@ class SentinelReplicationTest extends PredisTestCase
         $replication->getSentinelConnection();
     }
 
+    /**
+     * @group disconnected
+     */
+    public function testParametersForSentinelConnectionShouldNotUseDatabaseAndPassword()
+    {
+        $replication = $this->getReplicationConnection('svc', array(
+            'tcp://127.0.0.1:5381?alias=sentinel1&database=1&password=secret',
+        ));
+
+        $parameters = $replication->getSentinelConnection()->getParameters()->toArray();
+
+        $this->assertArrayNotHasKey('password', $parameters);
+        $this->assertArrayNotHasKey('database', $parameters);
+    }
+
+    /**
+     * @group disconnected
+     */
+    public function testParametersForSentinelConnectionHaveDefaultTimeout()
+    {
+        $replication = $this->getReplicationConnection('svc', array(
+            'tcp://127.0.0.1:5381?alias=sentinel',
+        ));
+
+        $parameters = $replication->getSentinelConnection()->getParameters()->toArray();
+
+        $this->assertArrayHasKey('timeout', $parameters);
+        $this->assertSame(0.100, $parameters['timeout']);
+    }
+
+    /**
+     * @group disconnected
+     */
+    public function testParametersForSentinelConnectionCanOverrideDefaultTimeout()
+    {
+        $replication = $this->getReplicationConnection('svc', array(
+            'tcp://127.0.0.1:5381?alias=sentinel&timeout=1',
+        ));
+
+        $parameters = $replication->getSentinelConnection()->getParameters()->toArray();
+
+        $this->assertArrayHasKey('timeout', $parameters);
+        $this->assertSame('1', $parameters['timeout']);
+    }
+
+    /**
+     * @group disconnected
+     */
+    public function testConnectionParametersInstanceForSentinelConnectionIsNotModified()
+    {
+        $originalParameters = Connection\Parameters::create(
+            'tcp://127.0.0.1:5381?alias=sentinel1&database=1&password=secret'
+        );
+
+        $replication = $this->getReplicationConnection('svc', array($originalParameters));
+
+        $parameters = $replication->getSentinelConnection()->getParameters();
+
+        $this->assertSame($originalParameters, $parameters);
+        $this->assertNotNull($parameters->password);
+        $this->assertNotNull($parameters->database);
+    }
+
     /**
      * @group disconnected
      */