diff --git a/README.md b/README.md
index a6e18e0..96346ce 100644
--- a/README.md
+++ b/README.md
@@ -264,7 +264,9 @@ Corresponding `work-groups` Group Listing document:
 ```ttl
 # Contents of https://alice.example.com/work-groups
 @prefix    acl:  <http://www.w3.org/ns/auth/acl#>.
+@prefix     dc:  <http://purl.org/dc/elements/1.1/>.
 @prefix  vcard:  <http://www.w3.org/2006/vcard/ns#>.
+@prefix    xsd:  <http://www.w3.org/2001/XMLSchema#>.
 
 <#Accounting>
     a                vcard:Group;