diff --git a/roles/docker/templates/restic/failure.sh.j2 b/roles/docker/templates/restic/failure.sh.j2
index 6a11cde..22b1fec 100644
--- a/roles/docker/templates/restic/failure.sh.j2
+++ b/roles/docker/templates/restic/failure.sh.j2
@@ -6,7 +6,7 @@ From: Restic backup <{{ services.restic.mail_from }}>
 To: admin@data.coop
 Subject: Restic backup failed
 Date: $(date -R)
-Message-ID: $(date +%s.%N)@{{ services.restic.domain }}
+Message-ID: <$(date +%s.%N)@{{ services.restic.domain }}>
 
 Dear sir or madam,