diff --git a/io_mesh_stl/blender_utils.py b/io_mesh_stl/blender_utils.py
index 751f258634636252eb1dced8cb7c67a435ceaa49..3d0ef076b7e908bfa5f74acd9f58069635b17f32 100644
--- a/io_mesh_stl/blender_utils.py
+++ b/io_mesh_stl/blender_utils.py
@@ -1,3 +1,23 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  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, or (at your option) any later version.
+#
+#  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, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
 import bpy
 
 
diff --git a/io_mesh_stl/stl_utils.py b/io_mesh_stl/stl_utils.py
index 9524ecb3dcfafcd9df87d093591d30ade02233e8..e320774dca8268572e15bf22475840c1a2370369 100644
--- a/io_mesh_stl/stl_utils.py
+++ b/io_mesh_stl/stl_utils.py
@@ -1,3 +1,23 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  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, or (at your option) any later version.
+#
+#  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, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
 '''
 Import and export STL files