diff --git a/lexicons/site/exosphere/sphere.label.json b/lexicons/site/exosphere/sphere.label.json
index e3cd8c5..c530e3c 100644
--- a/lexicons/site/exosphere/sphere.label.json
+++ b/lexicons/site/exosphere/sphere.label.json
@@ -23,6 +23,11 @@
             "items": { "type": "string" },
             "maxLength": 50,
             "description": "Label names assigned to the entity. Replaces any previous set."
+          },
+          "updatedAt": {
+            "type": "string",
+            "format": "datetime",
+            "maxLength": 64
           }
         }
       }