diff --git a/includes/database/pgsql/database.inc b/includes/database/pgsql/database.inc
index 0f5627c2a28..ec68c3a396a 100644
--- a/includes/database/pgsql/database.inc
+++ b/includes/database/pgsql/database.inc
@@ -26,6 +26,11 @@ class DatabaseConnection_pgsql extends DatabaseConnection {
       $connection_options['port'] = 5432;
     }
 
+    // PostgreSQL in trust mode doesn't require a password to be supplied.
+    if (empty($connection_options['password'])) {
+      $connection_options['password'] = null;
+    }
+
     $dsn = 'pgsql:host=' . $connection_options['host'] . ' dbname=' . $connection_options['database'] . ' port=' . $connection_options['port'];
     parent::__construct($dsn, $connection_options['username'], $connection_options['password'], array(
       // Convert numeric values to strings when fetching.