diff --git a/src/FitText.js b/src/FitText.js
index a708344..19e8fe6 100644
--- a/src/FitText.js
+++ b/src/FitText.js
@@ -114,7 +114,7 @@ FitText.propTypes = {
   children: PropTypes.oneOfType([PropTypes.element, PropTypes.string]),
   compressor: PropTypes.number,
   debounce: PropTypes.number,
-  defaultFontSize: PropTypes.string,
+  defaultFontSize: PropTypes.oneOfType([PropTypes.number, PropTypes.string]),
   minFontSize: PropTypes.number,
   maxFontSize: PropTypes.number,
   parent: PropTypes.oneOfType([PropTypes.string, PropTypes.object]),