diff --git a/README.rst b/README.rst
index 8c9b945..b193291 100644
--- a/README.rst
+++ b/README.rst
@@ -1,2 +1,19 @@
+=======
 postgres
 ========
+
+.. note::
+
+    See the full `Salt Formulas installation and usage instructions
+    <http://docs.saltstack.com/topics/conventions/formulas.html>`_.
+
+Available states
+================
+
+.. contesnt::
+    :local:
+
+``postgres``
+------------
+
+Installs the postgresql package.
diff --git a/postgres/init.sls b/postgres/init.sls
index 727c4fc..d591ccc 100644
--- a/postgres/init.sls
+++ b/postgres/init.sls
@@ -1,9 +1,7 @@
-# pkg.install
-postgresql:
-  pkg.installed:
-    {% if grains['os_family'] == 'RedHat' %}
-    - name: postgresql
-    {% elif grains['os_family'] == 'Debian' %}
-    - name: postgresql-9.1
-    {% endif %}
+{% from postgres/map.jinja import postgres with context %}
+
+postgresql:
+  pkg:
+    - installed
+    - name: {{ postgres.pkg }}
 
diff --git a/postgres/map.jinja b/postgres/map.jinja
new file mode 100644
index 0000000..03963cb
--- /dev/null
+++ b/postgres/map.jinja
@@ -0,0 +1,8 @@
+{% set postgres = salt['grains.filter_by']({
+    'Debian': {
+        'pkg': 'postgresql-9.1',
+    },
+    'RedHat': {
+        'pkg': 'postgresql',
+    },
+}, merge=salt['pillar.get']('postgres:lookup')) %}