diff --git a/cataloguing/value_builder/validate_isbn.pl b/cataloguing/value_builder/validate_isbn.pl
index 4955796149..5e51a49576 100755
--- a/cataloguing/value_builder/validate_isbn.pl
+++ b/cataloguing/value_builder/validate_isbn.pl
@@ -15,7 +15,7 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
-# along with Koha; if not, see <http://www.gnu.org/licenses>.
+# along with Koha; if not, see <https://www.gnu.org/licenses>.
 
 use Modern::Perl;
 use CGI qw ( -utf8 );