diff --git a/how_to b/how_to
index 398e2b7..cbd8319 100644
--- a/how_to
+++ b/how_to
@@ -282,13 +282,17 @@ Wallpapers :
 Drag & drop files:
     dragon : https://github.com/mwh/dragon
 
-Fix hardware clock (with chrony):
+Fix hardware clock (with chrony / NTC):
     sudo chronyc
         makestep
         trimrtc
         quit
     Alternative to trimrtc:
         sudo hwclock --systohc
+    513 RTC driver not running:
+        In /etc/chrony.conf
+            comment all `rtcsync`
+            uncomment `rtcfile ...`
 
 Network Manager:
     # Yes it is bloated, but it #JustWorks(TM)