diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/MatteryScreen.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/MatteryScreen.kt
index aacde08a7..1f3960e11 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/MatteryScreen.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/client/screen/MatteryScreen.kt
@@ -582,9 +582,9 @@ abstract class MatteryScreen<T : MatteryMenu>(menu: T, inventory: Inventory, tit
 	}
 
 	override fun containerTick() {
-		for (panel in panels) {
-			panel.tick()
-		}
+		val copy = ArrayList<EditablePanel<*>>(panels.size)
+		for (panel in panels) copy.add(panel)
+		for (panel in copy) panel.tick()
 	}
 
 	companion object {