diff --git a/packages/vaadin-list-box/src/vaadin-list-box.d.ts b/packages/vaadin-list-box/src/vaadin-list-box.d.ts
index 36effaa095d..3d31cbaa9ff 100644
--- a/packages/vaadin-list-box/src/vaadin-list-box.d.ts
+++ b/packages/vaadin-list-box/src/vaadin-list-box.d.ts
@@ -17,7 +17,7 @@ export type  ListBoxSelectedChanged = CustomEvent<{ value: number }>;
 /**
  * Fired when the `selectedValues` property changes.
  */
-export type  ListBoxSelectedValuesChanged = CustomEvent<{ value: Array<string> }>;
+export type  ListBoxSelectedValuesChanged = CustomEvent<{ value: Array<number> }>;
 
 export interface ListBoxElementEventMap {
   'items-changed': ListBoxItemsChanged;
diff --git a/packages/vaadin-list-box/test/typings/list-box.types.ts b/packages/vaadin-list-box/test/typings/list-box.types.ts
index eae762b4391..edd08cf3a51 100644
--- a/packages/vaadin-list-box/test/typings/list-box.types.ts
+++ b/packages/vaadin-list-box/test/typings/list-box.types.ts
@@ -13,5 +13,5 @@ listBox.addEventListener('selected-changed', (event) => {
 });
 
 listBox.addEventListener('selected-values-changed', (event) => {
-  assert<string[]>(event.detail.value);
+  assert<number[]>(event.detail.value);
 });
diff --git a/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.d.ts b/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.d.ts
index 8fc32cb8b3f..6ee9bec1ef0 100644
--- a/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.d.ts
+++ b/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.d.ts
@@ -21,7 +21,7 @@ interface MultiSelectListMixin extends ListMixin {
    * Array of indexes of the items selected in the items array
    * Note: Not updated when used in single selection mode.
    */
-  selectedValues: string[] | null | undefined;
+  selectedValues: number[] | null | undefined;
 
   _onMultipleClick(event: MouseEvent): void;
 }
diff --git a/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.js b/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.js
index 6a6e1398237..c6c63d35d65 100644
--- a/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.js
+++ b/packages/vaadin-list-mixin/vaadin-multi-select-list-mixin.js
@@ -28,7 +28,7 @@ export const MultiSelectListMixin = (superClass) =>
         /**
          * Array of indexes of the items selected in the items array
          * Note: Not updated when used in single selection mode.
-         * @type {string[] | null | undefined}
+         * @type {number[] | null | undefined}
          */
         selectedValues: {
           type: Array,