diff --git a/cirq-core/cirq/transformers/noise_adding.py b/cirq-core/cirq/transformers/noise_adding.py
index 2f2b0b0284e..8ac63bbb364 100644
--- a/cirq-core/cirq/transformers/noise_adding.py
+++ b/cirq-core/cirq/transformers/noise_adding.py
@@ -1,3 +1,17 @@
+# Copyright 2024 The Cirq Developers
+#
+# 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
+#
+#     https://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 collections.abc import Mapping
 
 import cirq
diff --git a/cirq-core/cirq/transformers/noise_adding_test.py b/cirq-core/cirq/transformers/noise_adding_test.py
index 7a859e2aaf7..803dd5f7cfa 100644
--- a/cirq-core/cirq/transformers/noise_adding_test.py
+++ b/cirq-core/cirq/transformers/noise_adding_test.py
@@ -1,3 +1,17 @@
+# Copyright 2024 The Cirq Developers
+#
+# 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
+#
+#     https://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.
+
 import cirq
 import cirq.transformers.noise_adding as na