diff --git a/letsencrypt.sh b/letsencrypt.sh
index 2bdc7a1..b1f3622 100755
--- a/letsencrypt.sh
+++ b/letsencrypt.sh
@@ -25,7 +25,7 @@ BASEDIR="${SCRIPTDIR}"
 # Create (identifiable) temporary files
 _mktemp() {
   # shellcheck disable=SC2068
-  mktemp ${@:-} letsencrypt.sh-XXXXXX
+  mktemp ${@:-} "${TMPDIR:-/tmp}/letsencrypt.sh-XXXXXX"
 }
 
 # Check for script dependencies