diff --git a/Library/Homebrew/exceptions.rb b/Library/Homebrew/exceptions.rb
index a45a5de772..9cb0fcb9cb 100644
--- a/Library/Homebrew/exceptions.rb
+++ b/Library/Homebrew/exceptions.rb
@@ -83,7 +83,7 @@ module Homebrew
   class InstallationError < RuntimeError
     attr_reader :formula
 
-    def initialize formula, message=""
+    def initialize(formula, message)
       super message
       @formula = formula
     end