1 files changed, 18 insertions, 6 deletions
diff --git a/Library/Formula/git-hg.rb b/Library/Formula/git-hg.rb
index 153062fee..fac0be430 100644
--- a/Library/Formula/git-hg.rb
+++ b/Library/Formula/git-hg.rb
@@ -1,16 +1,28 @@
 require 'formula'
 
+class HgInstalled < Requirement
+  def message; <<-EOS.undent
+    Mercurial is required to use this software.
+
+    You can install this with Homebrew using:
+      brew install mercurial
+
+    Or you can use an official installer from:
+      http://mercurial.selenic.com/
+    EOS
+  end
+  def satisfied?
+    which 'hg'
+  end
+end
+
 class GitHg < Formula
   head 'https://github.com/offbytwo/git-hg.git'
   homepage 'http://offbytwo.com/git-hg/'
 
-  def install
-    unless which 'hg'
-      puts "You may need to install Mercurial before using this software:"
-      puts "  brew install mercurial"
-    end
+  depends_on HgInstalled.new
 
+  def install
     prefix.install Dir['*']
   end
 end
-