diff --git a/superset-frontend/temporary_superset_ui/superset-ui/plugins/legacy-preset-chart-nvd3/src/PropTypes.js b/superset-frontend/temporary_superset_ui/superset-ui/plugins/legacy-preset-chart-nvd3/src/PropTypes.js
index 171e91cc66..9c13087ba4 100644
--- a/superset-frontend/temporary_superset_ui/superset-ui/plugins/legacy-preset-chart-nvd3/src/PropTypes.js
+++ b/superset-frontend/temporary_superset_ui/superset-ui/plugins/legacy-preset-chart-nvd3/src/PropTypes.js
@@ -74,6 +74,6 @@ export const annotationLayerType = PropTypes.shape({
   showMarkers: PropTypes.bool,
   sourceType: PropTypes.string,
   style: PropTypes.string,
-  value: PropTypes.number,
+  value: PropTypes.oneOfType([PropTypes.number, PropTypes.string]),
   width: PropTypes.number,
 });