diff --git a/changelog.d/16359.misc b/changelog.d/16359.misc
new file mode 100644
index 000000000000..8752085fc6f4
--- /dev/null
+++ b/changelog.d/16359.misc
@@ -0,0 +1 @@
+Add missing licence header.
diff --git a/synapse/rest/models.py b/synapse/rest/models.py
index ac39cda8e5e9..d47de5c19e23 100644
--- a/synapse/rest/models.py
+++ b/synapse/rest/models.py
@@ -1,3 +1,16 @@
+# Copyright 2022 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 from pydantic import BaseModel, Extra