diff --git a/Library/Homebrew/brew.rb b/Library/Homebrew/brew.rb
index d1d342cfcd..1423097280 100644
--- a/Library/Homebrew/brew.rb
+++ b/Library/Homebrew/brew.rb
@@ -121,7 +121,7 @@ begin
     possible_tap = Tap.fetch(possible_tap.first) if possible_tap
 
     if !possible_tap || possible_tap.installed? || Tap.untapped_official_taps.include?(possible_tap.name)
-      if cmd == 'cask' # Check for cask explicitly because it's very common in old guides
+      if cmd == "cask" # Check for cask explicitly because it's very common in old guides
         odie "`brew cask <command>` is no longer supported. Use `brew <command> --cask` instead."
       end
       odie "Unknown command: #{cmd}"