diff --git a/src/components/treeselect/TreeSelect.vue b/src/components/treeselect/TreeSelect.vue
index fece5613f..89be02b17 100644
--- a/src/components/treeselect/TreeSelect.vue
+++ b/src/components/treeselect/TreeSelect.vue
@@ -180,6 +180,7 @@ export default {
                 case 40:
                     if (!this.overlayVisible && event.altKey) {
                         this.show();
+                        event.preventDefault();
                     }
                 break;