diff --git a/sdmx/rest/common.py b/sdmx/rest/common.py
index 304ea160..d1190f80 100644
--- a/sdmx/rest/common.py
+++ b/sdmx/rest/common.py
@@ -15,6 +15,7 @@
 CLASS_NAME = {
     "dataflow": "DataflowDefinition",
     "datastructure": "DataStructureDefinition",
+    "metadatastructure": "MetadataStructureDefinition",
 }
 
 # Inverse of :data:`CLASS_NAME`.
diff --git a/sdmx/tests/test_model.py b/sdmx/tests/test_model.py
index fc181703..629ca208 100644
--- a/sdmx/tests/test_model.py
+++ b/sdmx/tests/test_model.py
@@ -216,6 +216,7 @@ def test_complete(module, extra):
         (dict(name=Resource.conceptscheme), model.ConceptScheme),
         (dict(name=Resource.contentconstraint), v21.ContentConstraint),
         (dict(name=Resource.dataflow), v21.DataflowDefinition),
+        (dict(name=Resource.metadatastructure), v21.MetadataStructureDefinition),
         (dict(name=Resource.organisationscheme), model.OrganisationScheme),
         (dict(name=Resource.provisionagreement), v21.ProvisionAgreement),
         pytest.param(