diff --git a/slack-mathbot/commands/calculate.rb b/slack-mathbot/commands/calculate.rb
index 04b860f..9a84696 100644
--- a/slack-mathbot/commands/calculate.rb
+++ b/slack-mathbot/commands/calculate.rb
@@ -5,7 +5,7 @@ module SlackMathbot
       command 'calculate'
 
       def self.call(client, data, match)
-        send_message client, data.channel, :expression
+        send_message client, data.channel, [:expression]
         result = Dentaku::Calculator.new.evaluate(match[:expression])
 		#if match.names.include?('expression')
         result = result.to_s if result