diff --git a/lib/db/install.xml b/lib/db/install.xml
index fcc226d84d26..1f805f10199f 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -117,7 +117,7 @@
         <FIELD NAME="idnumber" TYPE="char" LENGTH="100" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="description" TYPE="text" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="descriptionformat" TYPE="int" LENGTH="2" NOTNULL="true" DEFAULT="0" SEQUENCE="false"/>
-        <FIELD NAME="parent" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false"/>
+        <FIELD NAME="parent" TYPE="int" LENGTH="10" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="sortorder" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false"/>
         <FIELD NAME="coursecount" TYPE="int" LENGTH="10" NOTNULL="true" DEFAULT="0" SEQUENCE="false"/>
         <FIELD NAME="visible" TYPE="int" LENGTH="1" NOTNULL="true" DEFAULT="1" SEQUENCE="false"/>