diff --git a/core/database_api.php b/core/database_api.php
index f1f098bf6f..df9c15bf50 100644
--- a/core/database_api.php
+++ b/core/database_api.php
@@ -605,7 +605,8 @@ function db_index_exists( $p_table_name, $p_index_name ) {
  */
 function db_field_exists( $p_field_name, $p_table_name ) {
 	global $g_db;
-	return in_array( $p_field_name, $g_db->MetaColumnNames( $p_table_name ) );
+	$columns = db_field_names( $p_table_name );
+	return in_array( $p_field_name, $columns );
 }
 
 /**
@@ -615,7 +616,8 @@ function db_field_exists( $p_field_name, $p_table_name ) {
  */
 function db_field_names( $p_table_name ) {
 	global $g_db;
-	return $g_db->MetaColumnNames( $p_table_name );
+	$columns = $g_db->MetaColumnNames( $p_table_name );
+	return is_array( $columns ) ? $columns : array();
 }
 
 /**
diff --git a/manage_user_page.php b/manage_user_page.php
index 3779619041..c6d24480a2 100644
--- a/manage_user_page.php
+++ b/manage_user_page.php
@@ -44,7 +44,7 @@
 	$c_filter = '';
 
 	# Clean up the form variables
-	if ( !in_array( $f_sort, db_field_names( $t_user_table ) ) ) {
+	if ( !db_field_exists( $f_sort, $t_user_table ) ) {
         $c_sort = 'username';
     } else {
         $c_sort = addslashes($f_sort);