diff --git a/files/default/slack_handler_webhook.rb b/files/default/slack_handler_webhook.rb
index e0f02fb..468ef21 100644
--- a/files/default/slack_handler_webhook.rb
+++ b/files/default/slack_handler_webhook.rb
@@ -106,7 +106,7 @@ def request_body(message, text_attachment)
       body[:icon_emoji] = @icon_emoji
     end
     body[:channel] = @channel if @channel
-    body[:attachments] = [{ text: text_attachment }] unless text_attachment.nil?
+    body[:attachments] = [{ text: text_attachment.to_s }] unless text_attachment.nil?
     body.to_json
   end
 end