diff --git a/src/Monolog/Formatter/LogstashFormatter.php b/src/Monolog/Formatter/LogstashFormatter.php
index 938b595b..0c4fdcd4 100644
--- a/src/Monolog/Formatter/LogstashFormatter.php
+++ b/src/Monolog/Formatter/LogstashFormatter.php
@@ -84,7 +84,7 @@ class LogstashFormatter extends NormalizerFormatter
             $message['level'] = $record['level_name'];
         }
         if (isset($record['level'])) {
-            $message['level_num'] = $record['level'];
+            $message['monolog_level'] = $record['level'];
         }
         if ($this->applicationName) {
             $message['type'] = $this->applicationName;
diff --git a/tests/Monolog/Formatter/LogstashFormatterTest.php b/tests/Monolog/Formatter/LogstashFormatterTest.php
index cfe67a42..19b7652b 100644
--- a/tests/Monolog/Formatter/LogstashFormatterTest.php
+++ b/tests/Monolog/Formatter/LogstashFormatterTest.php
@@ -45,7 +45,7 @@ class LogstashFormatterTest extends \PHPUnit_Framework_TestCase
         $this->assertEquals('log', $message['message']);
         $this->assertEquals('meh', $message['channel']);
         $this->assertEquals('ERROR', $message['level']);
-        $this->assertEquals(Logger::ERROR, $message['level_num']);
+        $this->assertEquals(Logger::ERROR, $message['monolog_level']);
         $this->assertEquals('test', $message['type']);
         $this->assertEquals('hostname', $message['host']);