diff --git a/mesh_tissue/config.py b/mesh_tissue/config.py
index 380cb28185bb196619c4d3ff28c492403ad28673..0351ebc98e71a04002259cd6da8e27b2079abb80 100644
--- a/mesh_tissue/config.py
+++ b/mesh_tissue/config.py
@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
 import bpy
 from bpy.props import (
     IntProperty,
diff --git a/mesh_tissue/curves_tools.py b/mesh_tissue/curves_tools.py
index 5f6e07a41059a477cc9ba72365c203568be8c236..11a4ced7141dbb6bab466f217868c870d9e5b3c4 100644
--- a/mesh_tissue/curves_tools.py
+++ b/mesh_tissue/curves_tools.py
@@ -1,20 +1,4 @@
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 #                                                                              #
 #                        (c)   Alessandro Zomparelli                           #
diff --git a/mesh_tissue/material_tools.py b/mesh_tissue/material_tools.py
index a734abeb18ba175e497b174cada39580c928866c..b41568c40d3a2e19077949987e5facd53dfbc356 100644
--- a/mesh_tissue/material_tools.py
+++ b/mesh_tissue/material_tools.py
@@ -1,20 +1,4 @@
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 #                                                                              #
 #                          (c)  Alessandro Zomparelli                          #
diff --git a/mesh_tissue/polyhedra.py b/mesh_tissue/polyhedra.py
index d58f08aa3a0fe1d5397100a25dfe0f4df2dc11c9..bd5fca7825d84882e3c201c4f5d3362eafaf8e20 100644
--- a/mesh_tissue/polyhedra.py
+++ b/mesh_tissue/polyhedra.py
@@ -1,20 +1,4 @@
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # ---------------------------- ADAPTIVE DUPLIFACES --------------------------- #
 # ------------------------------- version 0.84 ------------------------------- #
diff --git a/mesh_tissue/tissue_properties.py b/mesh_tissue/tissue_properties.py
index 433e60ea2789d864b3204093ad42f6e8e4b22c93..bc06aefc9dc797e66edcf33a534f6eb3c5e9d1c8 100644
--- a/mesh_tissue/tissue_properties.py
+++ b/mesh_tissue/tissue_properties.py
@@ -1,20 +1,4 @@
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # ---------------------------- ADAPTIVE DUPLIFACES --------------------------- #
 # ------------------------------- version 0.84 ------------------------------- #
diff --git a/mesh_tissue/utils_pip.py b/mesh_tissue/utils_pip.py
index adfad77f78b3cc28d861788098cb05ed25944139..9e5e712d4876471dba76b12651ca2a3b1f3d5100 100644
--- a/mesh_tissue/utils_pip.py
+++ b/mesh_tissue/utils_pip.py
@@ -1,22 +1,4 @@
-# -*- coding:utf-8 -*-
-
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # <pep8 compliant>
 
diff --git a/mesh_tissue/weight_tools.py b/mesh_tissue/weight_tools.py
index ef83f1281c17408d084f6d1b6be54d0d1b4cc6a5..2736945eb571fe22ed14f0821a772c2ba0bd1c7f 100644
--- a/mesh_tissue/weight_tools.py
+++ b/mesh_tissue/weight_tools.py
@@ -1,20 +1,4 @@
-# ##### 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 #####
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 #-------------------------- COLORS / GROUPS EXCHANGER -------------------------#
 #                                                                              #