diff --git a/lib/components/Tab.js b/lib/components/Tab.js
index 51090143ed..2fdf59cb5e 100644
--- a/lib/components/Tab.js
+++ b/lib/components/Tab.js
@@ -4,7 +4,7 @@ import cx from 'classnames';
 
 function syncNodeAttributes(node, props) {
   if (props.selected) {
-    node.setAttribute('tabindex', 0);
+    node.setAttribute('tabindex', '0');
     node.setAttribute('selected', 'selected');
     if (props.focus) {
       node.focus();