diff --git a/packages/netlify-cms-widget-list/src/ListControl.js b/packages/netlify-cms-widget-list/src/ListControl.js
index baccefe9..8cfddc8e 100644
--- a/packages/netlify-cms-widget-list/src/ListControl.js
+++ b/packages/netlify-cms-widget-list/src/ListControl.js
@@ -147,7 +147,7 @@ export default class ListControl extends React.Component {
 
     const parsedValue = valueToString(listValue);
     this.setState({ value: parsedValue });
-    onChange(listValue.map(val => val.trim()));
+    onChange(List(listValue.map(val => val.trim())));
   };
 
   handleFocus = () => {