diff --git a/CRM/MembershipExtras/Hook/ValidateForm/UpdateSubscription.php b/CRM/MembershipExtras/Hook/ValidateForm/UpdateSubscription.php
index c18e5d33..937f68a4 100644
--- a/CRM/MembershipExtras/Hook/ValidateForm/UpdateSubscription.php
+++ b/CRM/MembershipExtras/Hook/ValidateForm/UpdateSubscription.php
@@ -54,6 +54,10 @@ public function __construct($form, &$fields, &$errors) {
    * Validates the subscription form submission
    */
   public function validate() {
+    if (empty($this->recurringContribution['frequency_unit'])) {
+      return;
+    }
+
     $this->validateCycleDay();
     $this->validateNextContributionDate();
   }