diff --git a/lib/document_stores/postgres.js b/lib/document_stores/postgres.js
index 67b1cb8..c712e1f 100644
--- a/lib/document_stores/postgres.js
+++ b/lib/document_stores/postgres.js
@@ -3,8 +3,7 @@
 var postgres = require('pg');
 var winston = require('winston');
 
-// create table entries (id SERIAL primary key, key varchar(255) not null, value text not null, expiration int);
-// CREATE UNIQUE INDEX unique_key ON entries (key);
+// create table entries (id serial primary key, key varchar(255) not null, value text not null, expiration int, unique(key));
 
 // A postgres document store
 var PostgresDocumentStore = function (options) {