diff --git a/db_structure.xml b/db_structure.xml
index d04c838d7cd..74e2805308a 100644
--- a/db_structure.xml
+++ b/db_structure.xml
@@ -552,6 +552,7 @@
    <field>
     <name>expiration</name>
     <type>timestamp</type>
+    <default></default>
     <notnull>false</notnull>
    </field>