diff --git a/src/Checkbox.jsx b/src/Checkbox.jsx
index 6dab02c..2d8f148 100644
--- a/src/Checkbox.jsx
+++ b/src/Checkbox.jsx
@@ -18,7 +18,7 @@ export default class Checkbox extends React.Component {
     onBlur: PropTypes.func,
     onChange: PropTypes.func,
     onClick: PropTypes.func,
-    tabIndex: PropTypes.string,
+    tabIndex: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
     readOnly: PropTypes.bool,
     autoFocus: PropTypes.bool,
     value: PropTypes.any,