diff --git a/src/Monolog/Handler/SlackHandler.php b/src/Monolog/Handler/SlackHandler.php
index c2c5a949..79c61615 100644
--- a/src/Monolog/Handler/SlackHandler.php
+++ b/src/Monolog/Handler/SlackHandler.php
@@ -110,6 +110,10 @@ class SlackHandler extends SocketHandler
         $dataArray = $this->slackRecord->getSlackData($record);
         $dataArray['token'] = $this->token;
 
+        if (!empty($dataArray['attachments'])) {
+            $dataArray['attachments'] = json_encode($dataArray['attachments']);
+        }
+
         return $dataArray;
     }
 
diff --git a/tests/Monolog/Handler/SlackHandlerTest.php b/tests/Monolog/Handler/SlackHandlerTest.php
index 5de7885f..b12b01f4 100644
--- a/tests/Monolog/Handler/SlackHandlerTest.php
+++ b/tests/Monolog/Handler/SlackHandlerTest.php
@@ -99,7 +99,7 @@ class SlackHandlerTest extends TestCase
         fseek($this->res, 0);
         $content = fread($this->res, 1024);
 
-        $this->assertRegexp('/%5Bcolor%5D='.$expectedColor.'/', $content);
+        $this->assertRegexp('/%22color%22%3A%22'.$expectedColor.'/', $content);
     }
 
     public function testWriteContentWithPlainTextMessage()