diff --git a/README.md b/README.md
index 33842a9..6f8bbfa 100644
--- a/README.md
+++ b/README.md
@@ -128,6 +128,8 @@ git config --get pullrequest.userlogin  # returns the github user login for the
 
  * `.git/user_login`: the user login of the pull request author
 
+ * `.git/head_sha`: the latest commit hash of the branch associated with the pull request
+
 #### Parameters
 
 * `git.depth`: *Optional.* If a positive integer is given, *shallow* clone the
diff --git a/assets/lib/commands/in.rb b/assets/lib/commands/in.rb
index 26eadab..ac8ffea 100755
--- a/assets/lib/commands/in.rb
+++ b/assets/lib/commands/in.rb
@@ -31,6 +31,7 @@ def output
           echo "#{pr['head']['ref']}" > branch
           echo "#{pr['base']['ref']}" > base_branch
           echo "#{pr['base']['user']['login']}" > userlogin
+          echo "#{pr['head']['sha']}" > head_sha
         BASH
       end
 
diff --git a/spec/commands/in_spec.rb b/spec/commands/in_spec.rb
index 314993d..960c999 100644
--- a/spec/commands/in_spec.rb
+++ b/spec/commands/in_spec.rb
@@ -52,7 +52,7 @@ def dest_dir
       end
 
       before(:all) do
-        stub_json('https://api.github.com:443/repos/jtarchie/test/pulls/1', html_url: 'http://example.com', number: 1, head: { ref: 'foo' }, base: { ref: 'master', user: { login: 'jtarchie' } })
+        stub_json('https://api.github.com:443/repos/jtarchie/test/pulls/1', html_url: 'http://example.com', number: 1, head: { ref: 'foo', sha: 'hash' }, base: { ref: 'master', user: { login: 'jtarchie' } })
         @output = get('version' => { 'ref' => @ref, 'pr' => '1' }, 'source' => { 'uri' => git_uri, 'repo' => 'jtarchie/test' })
       end
 
@@ -113,6 +113,11 @@ def dest_dir
         expect(value).to eq 'master'
       end
 
+      it 'creates a file that includes the hash of the branch  in the .git folder' do
+        value = File.read(File.join(dest_dir,'.git','head_sha')).strip()
+        expect(value).to eq 'hash'
+      end
+
     end
 
     context 'when the git clone fails' do