diff --git a/opentech/static_src/src/app/src/components/GroupedListing/index.js b/opentech/static_src/src/app/src/components/GroupedListing/index.js
index 8688306d702d986bb63814b109b0feb18cc1267b..f60e5665b8dd94dc2408491ea066d395bb2033b9 100644
--- a/opentech/static_src/src/app/src/components/GroupedListing/index.js
+++ b/opentech/static_src/src/app/src/components/GroupedListing/index.js
@@ -20,7 +20,7 @@ export default class GroupedListing extends React.Component {
             key: PropTypes.string.isRequired,
             display: PropTypes.string.isRequired,
             values: PropTypes.arrayOf(
-                PropTypes.oneOf(PropTypes.number, PropTypes.string),
+                PropTypes.oneOf([PropTypes.number, PropTypes.string]),
             )
         })),
         onItemSelection: PropTypes.func,