diff --git a/board/common/overlay/usr/share/post-upgrade/20190127.sh b/board/common/overlay/usr/share/post-upgrade/20190127.sh
index 0041888f94..a50b227922 100755
--- a/board/common/overlay/usr/share/post-upgrade/20190127.sh
+++ b/board/common/overlay/usr/share/post-upgrade/20190127.sh
@@ -15,7 +15,8 @@ function process_file() {
     # $1 - file path
     test -f $1 || return
     
-    cat $1 | to_uppercase > $1
+    cat $1 | to_uppercase > $1.new
+    mv $1.new $1
 }
 
 process_file /data/etc/os.conf