diff --git a/src/schema/vocab.rnc b/src/schema/vocab.rnc
index 4d41834816923cf581a60949662439105876d4eb..4363ff166786194ea722ff6ab5ad78f19492773a 100644
--- a/src/schema/vocab.rnc
+++ b/src/schema/vocab.rnc
@@ -27,6 +27,7 @@ skos.Concept =
    element skos:Concept {
       rdfPrimarySubject
     & Label+
+    & skos.altLabel*
     & skos.notation?
     & skos.inScheme
     & skos.match
@@ -61,4 +62,9 @@ skos.match =
    }*
  & element skos:related {
     rdfResource
- }*
\ No newline at end of file
+ }*
+
+skos.altLabel = element skos:altLabel {
+   attribute xml:lang { xsd:language }?,
+   text
+}
\ No newline at end of file