diff --git a/vendor/ego/lib/ego.ml b/vendor/ego/lib/ego.ml
index f41f588..e9db11f 100644
--- a/vendor/ego/lib/ego.ml
+++ b/vendor/ego/lib/ego.ml
@@ -1,3 +1,11 @@
+(*
+  This file includes modified code from the Ego project
+  (https://github.com/verse-lab/ego),
+  which is licensed under the GNU General Public License v3.0.
+
+  Modifications © 2025 Migyu Jo.
+  See LICENSE.GPL for full license text.
+*)
 module Id = Id
 module Basic = Basic
 module Generic = struct
diff --git a/vendor/ego/lib/equivalence.ml b/vendor/ego/lib/equivalence.ml
index e975684..eea51bf 100644
--- a/vendor/ego/lib/equivalence.ml
+++ b/vendor/ego/lib/equivalence.ml
@@ -1,3 +1,11 @@
+(*
+  This file includes modified code from the Ego project
+  (https://github.com/verse-lab/ego),
+  which is licensed under the GNU General Public License v3.0.
+
+  Modifications © 2025 Migyu Jo.
+  See LICENSE.GPL for full license text.
+*)
 open Containers
 (* module IntMap = Map.Make (Int) *)
 module IntMap = Hashtbl.Make (Int)
diff --git a/vendor/ego/lib/generic.ml b/vendor/ego/lib/generic.ml
index 8c54ede..8923a07 100644
--- a/vendor/ego/lib/generic.ml
+++ b/vendor/ego/lib/generic.ml
@@ -1,3 +1,11 @@
+(*
+  This file includes modified code from the Ego project
+  (https://github.com/verse-lab/ego),
+  which is licensed under the GNU General Public License v3.0.
+
+  Modifications © 2025 Migyu Jo.
+  See LICENSE.GPL for full license text.
+*)
 open [@warning "-33"] Containers
 open Language
 open Types
diff --git a/vendor/ego/lib/generic.mli b/vendor/ego/lib/generic.mli
index 1bfedbd..f56860f 100644
--- a/vendor/ego/lib/generic.mli
+++ b/vendor/ego/lib/generic.mli
@@ -1,3 +1,11 @@
+(*
+  This file includes modified code from the Ego project
+  (https://github.com/verse-lab/ego),
+  which is licensed under the GNU General Public License v3.0.
+
+  Modifications © 2025 Migyu Jo.
+  See LICENSE.GPL for full license text.
+*)
 open Language
 
 type ('node, 'data) eclass = {
diff --git a/vendor/ego/lib/language.ml b/vendor/ego/lib/language.ml
index 0c92c99..60cb4b4 100644
--- a/vendor/ego/lib/language.ml
+++ b/vendor/ego/lib/language.ml
@@ -1,3 +1,11 @@
+(*
+  This file includes modified code from the Ego project
+  (https://github.com/verse-lab/ego),
+  which is licensed under the GNU General Public License v3.0.
+
+  Modifications © 2025 Migyu Jo.
+  See LICENSE.GPL for full license text.
+*)
 open Containers
 module StringSet = Set.Make(String)
 module StringMap = Stdlib.Map.Make(String)