diff --git a/assets/js/src/form_editor/blocks/add_custom_field/add_custom_field_form.jsx b/assets/js/src/form_editor/blocks/add_custom_field/add_custom_field_form.jsx
index 6dab4a955e..ba4db2128e 100644
--- a/assets/js/src/form_editor/blocks/add_custom_field/add_custom_field_form.jsx
+++ b/assets/js/src/form_editor/blocks/add_custom_field/add_custom_field_form.jsx
@@ -47,7 +47,7 @@ const AddCustomFieldForm = ({ dateSettings, onSubmit }) => {
   const [fieldName, setFieldName] = useState(null);
   const [fieldSettings, setFieldSettings] = useState({});
 
-  const canSubmit = fieldName && !isEmpty(fieldSettings);
+  const canSubmit = fieldName && !isEmpty(fieldSettings) && (fieldSettings.isValid !== false);
   const defaultType = dateSettings.dateTypes[0].value;
   const defaultFormat = dateSettings.dateFormats[defaultType][0];
 
diff --git a/assets/js/src/form_editor/blocks/custom_checkbox/custom_field_settings.jsx b/assets/js/src/form_editor/blocks/custom_checkbox/custom_field_settings.jsx
index cd31e1a531..ffae76abce 100644
--- a/assets/js/src/form_editor/blocks/custom_checkbox/custom_field_settings.jsx
+++ b/assets/js/src/form_editor/blocks/custom_checkbox/custom_field_settings.jsx
@@ -4,6 +4,7 @@ import {
   Button,
   ToggleControl,
 } from '@wordpress/components';
+import { isEmpty } from 'lodash';
 import PropTypes from 'prop-types';
 import MailPoet from 'mailpoet';
 import CustomFieldDelete from '../custom_field_delete.jsx';
@@ -26,12 +27,11 @@ const CustomFieldSettings = ({
     mandatory: localMandatory,
     isChecked: localIsChecked,
     checkboxLabel: localCheckboxLabel,
+    isValid: !isEmpty(localCheckboxLabel),
   }), [localMandatory, localIsChecked, localCheckboxLabel]);
 
   useEffect(() => {
-    if (onChange) {
-      onChange(localData);
-    }
+    onChange(localData);
   }, [localData, onChange]);
 
   return (
@@ -101,7 +101,7 @@ CustomFieldSettings.defaultProps = {
   checkboxLabel: '',
   isDeleting: false,
   onCustomFieldDelete: null,
-  onChange: null,
+  onChange: () => {},
 };
 
 export default CustomFieldSettings;