diff --git a/lib/exception_notifier/mattermost_notifier.rb b/lib/exception_notifier/mattermost_notifier.rb
index 86aca127..98d1d04a 100644
--- a/lib/exception_notifier/mattermost_notifier.rb
+++ b/lib/exception_notifier/mattermost_notifier.rb
@@ -111,6 +111,7 @@ def message_request
       def message_backtrace(size = 3)
         text = []
 
+        size = @backtrace.size < size ? @backtrace.size : size
         text << "### Backtrace"
         text << "```"
         size.times { |i| text << "* " + @backtrace[i] }