diff --git a/specification/network/resource-manager/Microsoft.Network/stable/2019-09-01/applicationGateway.json b/specification/network/resource-manager/Microsoft.Network/stable/2019-09-01/applicationGateway.json
index 130d6f29063a..36a46b9d63c0 100644
--- a/specification/network/resource-manager/Microsoft.Network/stable/2019-09-01/applicationGateway.json
+++ b/specification/network/resource-manager/Microsoft.Network/stable/2019-09-01/applicationGateway.json
@@ -1485,6 +1485,13 @@
         "firewallPolicy": {
           "$ref": "./network.json#/definitions/SubResource",
           "description": "Reference to the FirewallPolicy resource."
+        },
+        "hostnames": {
+          "type": "array",
+          "items": {
+            "type": "string"
+          },
+          "description": "List of Host names for HTTP Listener that allows special wildcard characters as well."
         }
       },
       "description": "Properties of HTTP listener of an application gateway."