diff --git a/wadsrc/static/zscript/engine/ui/menu/optionmenu.zs b/wadsrc/static/zscript/engine/ui/menu/optionmenu.zs
index 47ec02069..305dcddb4 100644
--- a/wadsrc/static/zscript/engine/ui/menu/optionmenu.zs
+++ b/wadsrc/static/zscript/engine/ui/menu/optionmenu.zs
@@ -203,7 +203,7 @@ class OptionMenu : Menu
 		}
 		else if (ev.type == UIEvent.Type_Char)
 		{
-			String key = String.Format("%c", ev.keyChar).MakeLower();
+			int key = String.CharLower(ev.keyChar);
 			int itemsNumber = mDesc.mItems.Size();
 			int direction = ev.IsAlt ? -1 : 1;
 			for (int i = 0; i < itemsNumber; ++i)
@@ -211,7 +211,7 @@ class OptionMenu : Menu
 				int index = (mDesc.mSelectedItem + direction * (i + 1) + itemsNumber) % itemsNumber;
 				if (!mDesc.mItems[index].Selectable()) continue;
 				String label = StringTable.Localize(mDesc.mItems[index].mLabel);
-				String firstLabelCharacter = String.Format("%c", label.GetNextCodePoint(0)).MakeLower();
+				int firstLabelCharacter = String.CharLower(label.GetNextCodePoint(0));
 				if (firstLabelCharacter == key)
 				{
 					mDesc.mSelectedItem = index;