diff --git a/types/index.esm.d.ts b/types/index.esm.d.ts
index e5f474d9473..235670cd899 100644
--- a/types/index.esm.d.ts
+++ b/types/index.esm.d.ts
@@ -3025,7 +3025,7 @@ export type TimeScaleOptions = CartesianScaleOptions & {
      * If `number`, the index of the first day of the week (0 - Sunday, 6 - Saturday).
      * @default false
      */
-    isoWeekday: false | number;
+    isoWeekday: boolean | number;
     /**
      * Sets how different time units are displayed.
      */