diff --git a/slack-mathbot/commands/calculate.rb b/slack-mathbot/commands/calculate.rb
index 394b628..2a961ea 100644
--- a/slack-mathbot/commands/calculate.rb
+++ b/slack-mathbot/commands/calculate.rb
@@ -1,3 +1,5 @@
+require Math
+
 module SlackMathbot
   module Commands
     class Calculate < SlackRubyBot::Commands::Base
@@ -5,8 +7,7 @@ module SlackMathbot
       command 'calculate'
 
       def self.call(client, data, match)
-        result = Dentaku::Calculator.new.evaluate(match[:expression])
-		#if match.names.include?('expression')
+        result = Dentaku::Calculator.new.evaluate(match[:expression]) if match.names.include?('expression')
         result = result.to_s if result
         if result && result.length > 0
           send_message client, data.channel, result