diff --git a/naive.go b/naive.go
index bf70903..cde236c 100644
--- a/naive.go
+++ b/naive.go
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Unlicense
+
 package gigaparsec
 
 func Bind2Naïve[In, Out, T, T2 any](
diff --git a/naïve_test.go b/naïve_test.go
index 7594bf1..9bb3f0a 100644
--- a/naïve_test.go
+++ b/naïve_test.go
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: Unlicense
+
 package gigaparsec_test
 
 import (