diff --git a/Library/Homebrew/requirements.rb b/Library/Homebrew/requirements.rb
index 73e0860b76..45c128303c 100644
--- a/Library/Homebrew/requirements.rb
+++ b/Library/Homebrew/requirements.rb
@@ -118,3 +118,12 @@ class GitDependency < Requirement
   default_formula 'git'
   satisfy { which('git') }
 end
+
+class Python27Dependency < Requirement
+  fatal true
+  default_formula 'python'
+  satisfy do
+    # Note that python -V outputs to stderr
+    `python -V 2>&1` =~ /^Python 2.7/
+  end
+end