diff --git a/crx-jsstrings b/crx-jsstrings
index d6a4b49..644c1a6 100755
--- a/crx-jsstrings
+++ b/crx-jsstrings
@@ -15,6 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #
+# SPDX-License-Identifier: GPL-3.0-or-later
 """Tool for extracting crx file from a tar archive."""
 
 import datetime