diff --git a/index.js b/index.js
index 5e5f2e9..996271d 100644
--- a/index.js
+++ b/index.js
@@ -26,7 +26,7 @@ function _inherits(subClass, superClass) { if (typeof superClass !== "function"
 var propTypes = {
   table: _propTypes2.default.string.isRequired,
   filename: _propTypes2.default.string.isRequired,
-  filetype: _propTypes2.default.string.isRequired,
+  filetype: _propTypes2.default.string,
   sheet: _propTypes2.default.string.isRequired,
   id: _propTypes2.default.string,
   className: _propTypes2.default.string,