diff --git a/build-containers.timer b/build-containers.timer
index 7e94554..806f8ab 100644
--- a/build-containers.timer
+++ b/build-containers.timer
@@ -2,8 +2,8 @@
 Description=Rebuild Forgejo Actions containers
 
 [Timer]
-# every two weeks (1st and 15th of the month)
-OnCalendar=*-*-1,15 03:00:00
+# every month (on 1st of the month)
+OnCalendar=*-*-1 03:00:00
 Persistent=true
 RandomizedDelaySec=2h