diff --git a/packages/cubejs-server-core/core/RefreshScheduler.js b/packages/cubejs-server-core/core/RefreshScheduler.js
index 4c8028c2a8369..833ded1d2d2d2 100644
--- a/packages/cubejs-server-core/core/RefreshScheduler.js
+++ b/packages/cubejs-server-core/core/RefreshScheduler.js
@@ -25,7 +25,7 @@ class RefreshScheduler {
             }))
         );
 
-      const extractDate = ({ data }) => data[0] && data[0][Object.keys(data[0])[0]];
+      const extractDate = ({ data }) => data[0] && data[0][Object.keys(data[0])[0]].toString();
 
       const baseQuery = {
         ...queryingOptions,