diff --git a/src/datetime.js b/src/datetime.js
index 902790945..40c1e6ae1 100644
--- a/src/datetime.js
+++ b/src/datetime.js
@@ -894,7 +894,7 @@ export default class DateTime {
 
   /**
    * Create an invalid DateTime.
-   * @param {DateTime} reason - simple string of why this DateTime is invalid. Should not contain parameters or anything else data-dependent
+   * @param {string} reason - simple string of why this DateTime is invalid. Should not contain parameters or anything else data-dependent.
    * @param {string} [explanation=null] - longer explanation, may include parameters and other useful debugging information
    * @return {DateTime}
    */