diff --git a/post-install.sh b/post-install.sh
index 2ece974..e4f07bb 100644
--- a/post-install.sh
+++ b/post-install.sh
@@ -68,7 +68,7 @@ EOM
 fi
 
 #preserve saved sketches during firmware update
-echo "/root/sketches" >> /etc/sysupgrade.conf
+echo "/root/sketches" >> $IPKG_INSTROOT/etc/sysupgrade.conf
 
 ### Finally make sure basic configuration is set correctly