diff --git a/le-dns/cloudflare-hook.sh b/le-dns/cloudflare-hook.sh
index 784bd41..00a01dd 100755
--- a/le-dns/cloudflare-hook.sh
+++ b/le-dns/cloudflare-hook.sh
@@ -19,4 +19,28 @@ function unchanged_cert {
     local DOMAIN="${1}" KEYFILE="${2}" CERTFILE="${3}" FULLCHAINFILE="${4}" CHAINFILE="${5}"
 }
 
-HANDLER=$1; shift; $HANDLER $@
+function invalid_challenge {
+    local DOMAIN="${1}" RESPONSE="${2}"
+}
+
+function request_failure {
+    local STATUSCODE="${1}" REASON="${2}" REQTYPE="${3}" HEADERS="${4}"
+}
+
+function generate_csr {
+    local DOMAIN="${1}" CERTDIR="${2}" ALTNAMES="${3}"
+}
+
+function startup_hook {
+    :
+}
+
+function exit_hook {
+    :
+}
+
+HANDLER="$1"; shift
+if [[ "${HANDLER}" =~ ^(deploy_challenge|clean_challenge|deploy_cert|unchanged_cert|invalid_challenge|request_failure|generate_csr|startup_hook|exit_hook)$ ]]; then
+    "$HANDLER" "$@"
+fi
+