diff --git a/filter.go b/filter.go
index f017576..f6e01a1 100644
--- a/filter.go
+++ b/filter.go
@@ -1,3 +1,18 @@
+/*
+ filter --- Simple interactive data filter for POSIX pipelines
+
+Copyright (c) 2022  Sameer Rahmani <lxsameer@gnu.org>
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package main
 
 import (
diff --git a/utils.go b/utils.go
index 5c6418f..393f3ec 100644
--- a/utils.go
+++ b/utils.go
@@ -1,3 +1,18 @@
+/*
+ filter --- Simple interactive data filter for POSIX pipelines
+
+Copyright (c) 2022  Sameer Rahmani <lxsameer@gnu.org>
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 2 of the License.
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package main
 
 import (