diff --git a/src/Kdyby/RabbitMq/DI/RabbitMqExtension.php b/src/Kdyby/RabbitMq/DI/RabbitMqExtension.php
index 2a6cf5eb..8240421d 100644
--- a/src/Kdyby/RabbitMq/DI/RabbitMqExtension.php
+++ b/src/Kdyby/RabbitMq/DI/RabbitMqExtension.php
@@ -89,6 +89,7 @@ class RabbitMqExtension extends Nette\DI\CompilerExtension
 	public $rpcClientDefaults = [
 		'connection' => 'default',
 		'expectSerializedResponse' => TRUE,
+		'contentType' => 'text/plain',
 	];
 
 	/**
@@ -428,7 +429,7 @@ protected function loadRpcClients($clients)
 
 			$builder->addDefinition($serviceName = $this->prefix('rpcClient.' . $name))
 				->setClass('Kdyby\RabbitMq\RpcClient', ['@' . $this->connectionsMeta[$config['connection']]['serviceId']])
-				->addSetup('initClient', [$config['expectSerializedResponse']])
+				->addSetup('initClient', [$config['expectSerializedResponse'], $config['contentType']])
 				->addTag(self::TAG_RPC_CLIENT)
 				->setAutowired(FALSE);
 
diff --git a/src/Kdyby/RabbitMq/RpcClient.php b/src/Kdyby/RabbitMq/RpcClient.php
index 88ff5edb..2a58595a 100644
--- a/src/Kdyby/RabbitMq/RpcClient.php
+++ b/src/Kdyby/RabbitMq/RpcClient.php
@@ -33,6 +33,11 @@ class RpcClient extends AmqpMember
 	 */
 	protected $expectSerializedResponse;
 
+	/**
+	 * @var string
+	 */
+	protected $contentType;
+
 	/**
 	 * @var int
 	 */
@@ -40,7 +45,7 @@ class RpcClient extends AmqpMember
 
 
 
-	public function initClient($expectSerializedResponse = true)
+	public function initClient($expectSerializedResponse = true, $contentType = 'text/plain')
 	{
 		list($this->queueName,,) = $this->getChannel()->queue_declare(
 			"",
@@ -51,6 +56,7 @@ public function initClient($expectSerializedResponse = true)
 		);
 
 		$this->expectSerializedResponse = $expectSerializedResponse;
+		$this->contentType = $contentType;
 	}
 
 
@@ -62,7 +68,7 @@ public function addRequest($msgBody, $server, $requestId = null, $routingKey = '
 		}
 
 		$msg = new AMQPMessage($msgBody, [
-			'content_type' => 'text/plain',
+			'content_type' => $this->contentType,
 			'reply_to' => $this->queueName,
 			'delivery_mode' => 1, // non durable
 			'expiration' => $expiration * 1000,