diff --git a/screenshot.timer b/screenshot.timer
index a545ace..d73b7de 100644
--- a/screenshot.timer
+++ b/screenshot.timer
@@ -2,8 +2,8 @@
 Description=Take a screenshot every minute
 
 [Timer]
-OnCalendar=*:*:00
-OnCalendar=*:*:30
+OnBootSec=30s
+OnUnitActiveSec=30s
 Persistent=true
 
 [Install]