diff --git a/Library/Homebrew/build.rb b/Library/Homebrew/build.rb
index 0f76c55d5d..9b501d4b33 100755
--- a/Library/Homebrew/build.rb
+++ b/Library/Homebrew/build.rb
@@ -123,7 +123,7 @@ def install f
       system "git init"
       system "git add -A"
     end
-    if ARGV.flag? '--interactive'
+    if ARGV.interactive?
       ohai "Entering interactive mode"
       puts "Type `exit' to return and finalize the installation"
       puts "Install to this prefix: #{f.prefix}"