diff --git a/base_classes/NXpdb.nxdl.xml b/base_classes/NXpdb.nxdl.xml
index 3bb17550a..cc6c270b5 100644
--- a/base_classes/NXpdb.nxdl.xml
+++ b/base_classes/NXpdb.nxdl.xml
@@ -24,6 +24,7 @@
 <definition xmlns="http://definition.nexusformat.org/nxdl/3.1"
 	category="base"
 	name="NXpdb"
+	version="1.0"
 	type="group"
 	extends="NXobject"
 	ignoreExtraGroups="true"