diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index 00678935d9..c9d1f42d65 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -538,9 +538,9 @@ class FormulaInstaller
     end
 
     formula.options.each do |opt|
-      name  = opt.name[/\A(.+)=\z$/, 1]
-      value = ARGV.value(name)
-      args << "--#{name}=#{value}" if name && value
+      name = opt.name[/^([^=])+=$/, 1]
+      value = ARGV.value(name) if name
+      args << "--#{name}=#{value}" if value
     end
 
     args