diff --git a/site-modules/profile/files/weekly_report_bot/weekly-report-bot b/site-modules/profile/files/weekly_report_bot/weekly-report-bot
--- a/site-modules/profile/files/weekly_report_bot/weekly-report-bot
+++ b/site-modules/profile/files/weekly_report_bot/weekly-report-bot
@@ -5,7 +5,7 @@
 /usr/lib/sendmail -t <<EOF
 From: Weekly report bot <swh-devel@inria.fr>
 To: $DEST
-Subject: [Weekly Report] Week $(date +%G/%V)
+Subject: [Weekly Report] Week $(date +%G-W%V)
 
 Beep boop, I'm a bot.