diff --git a/phpBB/includes/functions_user.php b/phpBB/includes/functions_user.php
index 10fb57ea97..83316be2a3 100644
--- a/phpBB/includes/functions_user.php
+++ b/phpBB/includes/functions_user.php
@@ -1948,6 +1948,27 @@ function validate_jabber($jid)
 	return false;
 }
 
+/**
+* Verifies whether a style ID corresponds to an active style.
+*
+* @param int $style_id The style_id of a style which should be checked if activated or not.
+* @return boolean
+*/
+function phpbb_style_is_active($style_id)
+{
+	global $db;
+
+	$sql = 'SELECT style_active
+		FROM ' . STYLES_TABLE . '
+		WHERE style_id = '. (int) $style_id;
+	$result = $db->sql_query($sql);
+
+	$style_is_active = (bool) $db->sql_fetchfield('style_active');
+	$db->sql_freeresult($result);
+
+	return $style_is_active;
+}
+
 /**
 * Remove avatar
 */
diff --git a/phpBB/includes/ucp/ucp_prefs.php b/phpBB/includes/ucp/ucp_prefs.php
index 13167b2b3d..17d7d23f02 100644
--- a/phpBB/includes/ucp/ucp_prefs.php
+++ b/phpBB/includes/ucp/ucp_prefs.php
@@ -61,7 +61,14 @@ class ucp_prefs
 
 				if ($submit)
 				{
-					$data['style'] = ($config['override_user_style']) ? $config['default_style'] : $data['style'];
+					if ($config['override_user_style'])
+					{
+						$data['style'] = (int) $config['default_style'];
+					}
+					else if (!phpbb_style_is_active($data['style']))
+					{
+						$data['style'] = (int) $user->data['user_style'];
+					}
 
 					$error = validate_data($data, array(
 						'dateformat'	=> array('string', false, 1, 30),
diff --git a/phpBB/install/database_update.php b/phpBB/install/database_update.php
index a1b7dcd47f..6097341ace 100644
--- a/phpBB/install/database_update.php
+++ b/phpBB/install/database_update.php
@@ -993,6 +993,8 @@ function database_update_info()
 		'3.0.10-RC2'	=> array(),
 		// No changes from 3.0.10-RC3 to 3.0.10
 		'3.0.10-RC3'	=> array(),
+		// No changes from 3.0.10 to 3.0.11-RC1
+		'3.0.10'		=> array(),
 
 		/** @todo DROP LOGIN_ATTEMPT_TABLE.attempt_id in 3.0.11-RC1 */
 	);
@@ -2024,6 +2026,32 @@ function change_database_data(&$no_updates, $version)
 		// No changes from 3.0.10-RC3 to 3.0.10
 		case '3.0.10-RC3':
 		break;
+		
+		// Changes from 3.0.10 to 3.0.11-RC1
+		case '3.0.10':
+			// Updates users having current style a deactivated one
+			$sql = 'SELECT style_id
+				FROM ' . STYLES_TABLE . '
+				WHERE style_active = 0';
+			$result = $db->sql_query($sql);
+
+			$deactivated_style_ids = array();
+			while ($style_id = $db->sql_fetchfield('style_id', false, $result))
+			{
+				$deactivated_style_ids[] = (int) $style_id;
+			}
+			$db->sql_freeresult($result);
+
+			if (!empty($deactivated_style_ids))
+			{
+				$sql = 'UPDATE ' . USERS_TABLE . '
+					SET user_style = ' . (int) $config['default_style'] .'
+					WHERE ' . $db->sql_in_set('user_style', $deactivated_style_ids);
+				_sql($sql, $errored, $error_ary);
+			}
+
+			$no_updates = false;
+		break;
 	}
 }