diff --git a/Library/Homebrew/dev-cmd/pr-pull.rb b/Library/Homebrew/dev-cmd/pr-pull.rb
index 0b0951c8b4..1c4db1faf3 100644
--- a/Library/Homebrew/dev-cmd/pr-pull.rb
+++ b/Library/Homebrew/dev-cmd/pr-pull.rb
@@ -5,6 +5,7 @@ require "cli/parser"
 require "utils/github"
 require "tmpdir"
 require "bintray"
+require "formula"
 
 module Homebrew
   module_function