diff --git a/site-modules/profile/files/weekly_report_bot/weekly-report-bot b/site-modules/profile/files/weekly_report_bot/weekly-report-bot
index e76299b0..0d57853d 100755
--- a/site-modules/profile/files/weekly_report_bot/weekly-report-bot
+++ b/site-modules/profile/files/weekly_report_bot/weekly-report-bot
@@ -1,19 +1,19 @@
 #!/bin/bash
 
 DEST=swh-devel@inria.fr
 
 /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.
 
 This thread will contain reports on what the Software Heritage team members did
 over the last week. Please feel free to ask for more details, we'll be glad to
 oblige!
 
 Yours faithfully,
 -- 
 The Software Heritage weekly report bot
 EOF