diff --git a/include/dbstructure.php b/include/dbstructure.php
index f8d084437b..1e4790de2e 100644
--- a/include/dbstructure.php
+++ b/include/dbstructure.php
@@ -242,7 +242,7 @@ function update_structure($verbose, $action, $tables=null, $definition=null) {
 				if (!isset($database[$name]["fields"][$fieldname])) {
 					$sql2=db_add_table_field($fieldname, $parameters);
 					if ($sql3 == "") {
-						$sql3 = "ALTER TABLE `".$temp_name."` ".$sql2;
+						$sql3 = "ALTER" . $ignore . " TABLE `".$temp_name."` ".$sql2;
 					} else {
 						$sql3 .= ", ".$sql2;
 					}
@@ -253,7 +253,7 @@ function update_structure($verbose, $action, $tables=null, $definition=null) {
 					if ($current_field_definition != $new_field_definition) {
 						$sql2=db_modify_table_field($fieldname, $parameters);
 						if ($sql3 == "") {
-							$sql3 = "ALTER TABLE `".$temp_name."` ".$sql2;
+							$sql3 = "ALTER" . $ignore . " TABLE `".$temp_name."` ".$sql2;
 						} else {
 							$sql3 .= ", ".$sql2;
 						}