diff --git a/src/vs/base/browser/ui/selectBox/selectBoxCustom.ts b/src/vs/base/browser/ui/selectBox/selectBoxCustom.ts
index 988282c032cba2a9775fb7c63df62a992ee777c4..472557cea13a1459d8feabbf0604c972232b59c3 100644
--- a/src/vs/base/browser/ui/selectBox/selectBoxCustom.ts
+++ b/src/vs/base/browser/ui/selectBox/selectBoxCustom.ts
@@ -185,7 +185,7 @@ export class SelectBoxList implements ISelectBoxDelegate, IDelegate<ISelectOptio
 					showDropDown = true;
 				}
 			} else {
-				if (event.keyCode === KeyCode.DownArrow && event.altKey || event.keyCode === KeyCode.Space || event.keyCode === KeyCode.Enter) {
+				if (event.keyCode === KeyCode.DownArrow && event.altKey || event.keyCode === KeyCode.UpArrow && event.altKey || event.keyCode === KeyCode.Space || event.keyCode === KeyCode.Enter) {
 					showDropDown = true;
 				}
 			}