diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 3c7dec8e57..9e26a78bef 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -461,7 +461,7 @@ class FormulaInstaller
     when f.devel then args << "--devel"
     end
 
-    f.options.each do |opt, _|
+    f.options.each do |opt|
       name  = opt.name[/\A(.+)=\z$/, 1]
       value = ARGV.value(name)
       args << "--#{name}=#{value}" if name && value