diff --git a/readme.md b/readme.md
index 4e8764b2..296a782a 100644
--- a/readme.md
+++ b/readme.md
@@ -126,7 +126,7 @@ val gui = kSpigotGUI(GUIType.FIVE_BY_NINE) {
 
         // a button with a custom callback
         button(Slots.RowThreeSlotFive, ItemStack(Material.REPEATER)) {
-            it.gui[Slots.RowTwoSlotFive] = ItemStack(Material.values().random(), (1..64).random()
+            it.guiInstance[Slots.RowTwoSlotFive] = ItemStack(Material.values().random(), (1..64).random())
         }
 
         // a slot where player interaction is permitted