diff --git a/src/core/utils.js b/src/core/utils.js
index 9495d0fe..338399b3 100644
--- a/src/core/utils.js
+++ b/src/core/utils.js
@@ -501,7 +501,7 @@ export const validateString = ( val ) => {
 }
 
 export const validateDateTime = (val) => {
-    if (!isNaN(Date.parse(val))) {
+    if (isNaN(Date.parse(val))) {
         return "Value must be a DateTime"
     }
 }