diff --git a/assets/js/src/newsletters/templates.jsx b/assets/js/src/newsletters/templates.jsx
index 599246d3a5..9af2a5da8b 100644
--- a/assets/js/src/newsletters/templates.jsx
+++ b/assets/js/src/newsletters/templates.jsx
@@ -7,6 +7,7 @@ import TemplateBox from 'newsletters/templates/template_box.jsx';
 import ImportTemplate from 'newsletters/templates/import_template.jsx';
 import Hooks from 'wp-js-hooks';
 import _ from 'underscore';
+import PropTypes from 'prop-types';
 
 const getEditorUrl = id => `admin.php?page=mailpoet-newsletter-editor&id=${id}`;
 
@@ -217,7 +218,7 @@ class NewsletterTemplates extends React.Component {
       } else {
         templates = templates.map((template, index) => (
           <TemplateBox
-            key={index}
+            key={template.id}
             index={index}
             newsletterId={this.props.params.id}
             beforeDelete={() => this.setState({ loading: true })}
@@ -257,4 +258,10 @@ class NewsletterTemplates extends React.Component {
   }
 }
 
+NewsletterTemplates.propTypes = {
+  params: PropTypes.shape({
+    id: PropTypes.string.isRequired,
+  }).isRequired,
+};
+
 export default NewsletterTemplates;
diff --git a/assets/js/src/newsletters/templates/tabs.jsx b/assets/js/src/newsletters/templates/tabs.jsx
index 6284b81bd6..9c720b2645 100644
--- a/assets/js/src/newsletters/templates/tabs.jsx
+++ b/assets/js/src/newsletters/templates/tabs.jsx
@@ -20,8 +20,8 @@ Tabs.propTypes = {
   selected: PropTypes.string.isRequired,
   select: PropTypes.func.isRequired,
   tabs: PropTypes.arrayOf(PropTypes.shape({
-    label: PropTypes.func.isRequired,
-    name: PropTypes.func.isRequired,
+    label: PropTypes.string.isRequired,
+    name: PropTypes.string.isRequired,
   }).isRequired).isRequired,
 };