diff --git a/lib/db/install.xml b/lib/db/install.xml
index 7e6c04777f4..31e3ad53fc6 100644
--- a/lib/db/install.xml
+++ b/lib/db/install.xml
@@ -1499,7 +1499,7 @@
         <FIELD NAME="hashcode" TYPE="char" LENGTH="40" NOTNULL="true" SEQUENCE="false" COMMENT="sha1 hash of serialized qubaids_condition class. Unique for every combination of class name and property."/>
         <FIELD NAME="timemodified" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="questionid" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false"/>
-        <FIELD NAME="variant" TYPE="int" LENGTH="10" NOTNULL="true" SEQUENCE="false"/>
+        <FIELD NAME="variant" TYPE="int" LENGTH="10" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="subqid" TYPE="char" LENGTH="100" NOTNULL="true" SEQUENCE="false"/>
         <FIELD NAME="aid" TYPE="char" LENGTH="100" NOTNULL="false" SEQUENCE="false"/>
         <FIELD NAME="response" TYPE="text" NOTNULL="false" SEQUENCE="false"/>
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index 3c60f15b49b..8e1043d7fa7 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -3006,7 +3006,7 @@ function xmldb_main_upgrade($oldversion) {
 
         // Define field variant to be added to question_response_analysis.
         $table = new xmldb_table('question_response_analysis');
-        $field = new xmldb_field('variant', XMLDB_TYPE_INTEGER, '10', null, XMLDB_NOTNULL, null, 0, 'questionid');
+        $field = new xmldb_field('variant', XMLDB_TYPE_INTEGER, '10', null, null, null, null, 'questionid');
 
         // Conditionally launch add field variant.
         if (!$dbman->field_exists($table, $field)) {