diff --git a/includes/database.mysql.inc b/includes/database.mysql.inc
index 421ccbeb552bc3cd8a7d2a570ff98534f10e754c..262a28c1c1c6ebb0971d2868539873cb7f44d486 100644
--- a/includes/database.mysql.inc
+++ b/includes/database.mysql.inc
@@ -87,6 +87,7 @@ function db_connect($url) {
 
     // Show error screen otherwise
     drupal_maintenance_theme();
+    drupal_set_header('HTTP/1.1 503 Service Unavailable');
     drupal_set_title('Unable to connect to database server');
     print theme('maintenance_page', '<p>If you still have to install Drupal, proceed to the <a href="'. base_path() .'install.php">installation page</a>.</p>
 <p>If you have already finished installed Drupal, this either means that the username and password information in your <code>settings.php</code> file is incorrect or that we can\'t connect to the MySQL database server. This could mean your hosting provider\'s database server is down.</p>
diff --git a/includes/database.mysqli.inc b/includes/database.mysqli.inc
index de2c36af8cf15de4791863d66152b9a3e77eefcb..dd647165ec12a98e5c32a9a91990127afdbab258 100644
--- a/includes/database.mysqli.inc
+++ b/includes/database.mysqli.inc
@@ -73,6 +73,7 @@ function db_connect($url) {
   // Find all database connection errors and error 1045 for access denied for user account
   if (mysqli_connect_errno() >= 2000 || mysqli_connect_errno() == 1045) {
     drupal_maintenance_theme();
+    drupal_set_header('HTTP/1.1 503 Service Unavailable');
     drupal_set_title('Unable to connect to database server');
     print theme('maintenance_page', '<p>If you still have to install Drupal, proceed to the <a href="'. base_path() .'install.php">installation page</a>.</p>
 <p>If you have already finished installed Drupal, this either means that the username and password information in your <code>settings.php</code> file is incorrect or that we can\'t connect to the MySQL database server. This could mean your hosting provider\'s database server is down.</p>
diff --git a/includes/database.pgsql.inc b/includes/database.pgsql.inc
index a4b7301d4ff8849467feb54d3adddabee2d87396..f1500c8e8d5053dd543400515123d31335d0535e 100644
--- a/includes/database.pgsql.inc
+++ b/includes/database.pgsql.inc
@@ -84,6 +84,7 @@ function db_connect($url) {
   $connection = @pg_connect($conn_string);
   if (!$connection) {
     drupal_maintenance_theme();
+    drupal_set_header('HTTP/1.1 503 Service Unavailable');
     drupal_set_title('Unable to connect to database');
     print theme('maintenance_page', '<p>If you still have to install Drupal, proceed to the <a href="'. base_path() .'install.php">installation page</a>.</p>
 <p>If you have already finished installed Drupal, this either means that the username and password information in your <code>settings.php</code> file is incorrect or that we can\'t connect to the PostgreSQL database server. This could mean your hosting provider\'s database server is down.</p>