diff --git a/db/install.xml b/db/install.xml
index 1b9b74e..7d91234 100644
--- a/db/install.xml
+++ b/db/install.xml
@@ -40,7 +40,7 @@
         <FIELD NAME="id" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="true"/>
         <FIELD NAME="oidcuniqid" TYPE="char" LENGTH="255" NOTNULL="true" SEQUENCE="false" COMMENT="oidc uniqid"/>
         <FIELD NAME="username" TYPE="char" LENGTH="100" NOTNULL="true" SEQUENCE="false" COMMENT="username"/>
-        <FIELD NAME="userid" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false" COMMENT="moodle userid"/>
+        <FIELD NAME="userid" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false" DEFAULT="0" COMMENT="moodle userid"/>
         <FIELD NAME="oidcusername" TYPE="char" LENGTH="255" NOTNULL="true" SEQUENCE="false" COMMENT="oidc username"/>
         <FIELD NAME="scope" TYPE="text" NOTNULL="true" SEQUENCE="false" COMMENT="token scope"/>
         <FIELD NAME="resource" TYPE="char" LENGTH="127" NOTNULL="true" SEQUENCE="false" COMMENT="token resource"/>
diff --git a/db/upgrade.php b/db/upgrade.php
index de8b907..523795f 100644
--- a/db/upgrade.php
+++ b/db/upgrade.php
@@ -163,7 +163,7 @@ function xmldb_auth_oidc_upgrade($oldversion) {
 
     if ($result && $oldversion < 2018051700.01) {
         $table = new xmldb_table('auth_oidc_token');
-        $field = new xmldb_field('userid', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, null, 'username');
+        $field = new xmldb_field('userid', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, '0', 'username');
         if (!$dbman->field_exists($table, $field)) {
             $dbman->add_field($table, $field);
             $sql = 'SELECT tok.id, tok.username, u.username, u.id as userid