diff --git a/backbone/src/commonMain/kotlin/Backbone.kt b/backbone/src/commonMain/kotlin/Backbone.kt
index 64acb05..51ba2e5 100644
--- a/backbone/src/commonMain/kotlin/Backbone.kt
+++ b/backbone/src/commonMain/kotlin/Backbone.kt
@@ -1,3 +1,19 @@
+/*
+ * Copyright (c) 2022-2025, OpenSavvy and contributors.
+ *
+ * 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.
+ */
+
 package opensavvy.backbone
 
 /**
diff --git a/backbone/src/commonMain/kotlin/Ref.kt b/backbone/src/commonMain/kotlin/Ref.kt
index 858f5e3..674f722 100644
--- a/backbone/src/commonMain/kotlin/Ref.kt
+++ b/backbone/src/commonMain/kotlin/Ref.kt
@@ -1,3 +1,19 @@
+/*
+ * Copyright (c) 2022-2025, OpenSavvy and contributors.
+ *
+ * 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.
+ */
+
 package opensavvy.backbone
 
 import opensavvy.cache.Cache
diff --git a/backbone/src/commonTest/kotlin/BackboneCacheTest.kt b/backbone/src/commonTest/kotlin/BackboneCacheTest.kt
index c29beab..01e70bb 100644
--- a/backbone/src/commonTest/kotlin/BackboneCacheTest.kt
+++ b/backbone/src/commonTest/kotlin/BackboneCacheTest.kt
@@ -1,3 +1,19 @@
+/*
+ * Copyright (c) 2022-2025, OpenSavvy and contributors.
+ *
+ * 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.
+ */
+
 package opensavvy.backbone
 
 import arrow.core.raise.ensure