diff --git a/nucleus/src/arch/aarch64/caps/mod.rs b/nucleus/src/arch/aarch64/caps/mod.rs
index a30808e..1e0d9f4 100644
--- a/nucleus/src/arch/aarch64/caps/mod.rs
+++ b/nucleus/src/arch/aarch64/caps/mod.rs
@@ -1,3 +1,7 @@
+/*
+ * SPDX-License-Identifier: BlueOak-1.0.0
+ */
+
 //! AArch64-specific capabilities.
 
 mod asid_control_cap;