diff --git a/lcl/interfaces/cocoa/cocoawsstdctrls.pas b/lcl/interfaces/cocoa/cocoawsstdctrls.pas
index 70cf82b18d..89c747c346 100644
--- a/lcl/interfaces/cocoa/cocoawsstdctrls.pas
+++ b/lcl/interfaces/cocoa/cocoawsstdctrls.pas
@@ -1963,7 +1963,7 @@ begin
   list := GetListBox(ACustomListBox);
   if not Assigned(list) then Exit();
 
-  list.selectRowIndexes_byExtendingSelection(NSIndexSet.indexSetWithIndex(AIndex), True)
+  list.selectRowIndexes_byExtendingSelection(NSIndexSet.indexSetWithIndex(AIndex), false);
 end;
 
 class procedure TCocoaWSCustomListBox.SetSelectionMode(const ACustomListBox: TCustomListBox; const AExtendedSelect, AMultiSelect: boolean);