diff --git a/letsencrypt.sh b/letsencrypt.sh
index bedef33..b7e97d6 100755
--- a/letsencrypt.sh
+++ b/letsencrypt.sh
@@ -77,6 +77,8 @@ init_system() {
   load_config
 
   # Lockfile handling (prevents concurrent access)
+  LOCKDIR="$(dirname "${LOCKFILE}")"
+  [[ -w "${LOCKDIR}" ]] || _exiterr "Directory ${LOCKDIR} for LOCKFILE ${LOCKFILE} is now writable, aborting."
   ( set -C; date > "${LOCKFILE}" ) 2>/dev/null || _exiterr "Lock file '${LOCKFILE}' present, aborting."
   remove_lock() { rm -f "${LOCKFILE}"; }
   trap 'remove_lock' EXIT