diff --git a/specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2020-04-01/cosmos-db.json b/specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2020-04-01/cosmos-db.json
index d42b4c445ae0..77755fb138f9 100644
--- a/specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2020-04-01/cosmos-db.json
+++ b/specification/cosmos-db/resource-manager/Microsoft.DocumentDB/stable/2020-04-01/cosmos-db.json
@@ -5281,6 +5281,7 @@
           "readOnly": true
         },
         "_ts": {
+          "type": "number",
           "description": "A system generated property that denotes the last updated timestamp of the resource.",
           "readOnly": true
         },