diff --git a/app/v2/template/template_schemas.py b/app/v2/template/template_schemas.py
index 38892fb99..a9c9afece 100644
--- a/app/v2/template/template_schemas.py
+++ b/app/v2/template/template_schemas.py
@@ -66,9 +66,11 @@ post_template_preview_response = {
         "version": {"type": "integer"},
         "body": {"type": "string"},
         "subject": {"type": ["string", "null"]},
-        "postage": {"type": "string"}
+        "postage": {"type": "string"},
+        "html": {"type": ["string", "null"]},
     },
-    "required": ["id", "type", "version", "body"]
+    "required": ["id", "type", "version", "body"],
+    "additionalProperties": False,
 }
 
 
diff --git a/tests/app/v2/template/test_template_schemas.py b/tests/app/v2/template/test_template_schemas.py
index f5a89b922..de84ad661 100644
--- a/tests/app/v2/template/test_template_schemas.py
+++ b/tests/app/v2/template/test_template_schemas.py
@@ -71,17 +71,16 @@ valid_json_post_response = {
     'id': str(uuid.uuid4()),
     'type': 'email',
     'version': 1,
-    'created_by': 'someone@test.com',
-    'body': 'some body'
+    'body': 'some body',
 }
 
 valid_json_post_response_with_optionals = {
     'id': str(uuid.uuid4()),
     'type': 'email',
     'version': 1,
-    'created_by': 'someone@test.com',
     'body': "some body",
-    'subject': 'some subject'
+    'subject': 'some subject',
+    'html': '<p>some body</p>',
 }