diff --git a/thinkfan-confgen b/thinkfan-confgen
index 66ebdcb..bf6b0a4 100755
--- a/thinkfan-confgen
+++ b/thinkfan-confgen
@@ -1,7 +1,14 @@
 #!/usr/bin/env bash
 set -o errexit
+set -o pipefail
 
 main() {
+  if [[ -f "${1}" ]]; then
+    exec 1>"${1}"
+  fi
+
+  printf "# thinkfan-confgen created %s\n" "$(date -u)"
+
   find /sys -type f -name 'temp*_input' | while read -r line; do
     echo "hwmon ${line}"
   done