diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/capability/CombinedItemHandler.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/capability/CombinedItemHandler.kt
index b43fc9121..450e614cd 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/capability/CombinedItemHandler.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/capability/CombinedItemHandler.kt
@@ -3,6 +3,7 @@ package ru.dbotthepony.mc.otm.capability
 import com.google.common.collect.ImmutableList
 import net.minecraft.world.item.ItemStack
 import net.minecraftforge.items.IItemHandler
+import ru.dbotthepony.mc.otm.container.ContainerHandler
 import java.util.stream.Stream
 
 class CombinedItemHandler(val handlers: ImmutableList<IItemHandler>) : IItemHandler {
@@ -10,12 +11,20 @@ class CombinedItemHandler(val handlers: ImmutableList<IItemHandler>) : IItemHand
 	constructor(handlers: Collection<IItemHandler>) : this(ImmutableList.copyOf(handlers))
 	constructor(vararg handlers: IItemHandler) : this(ImmutableList.copyOf(handlers))
 
+	private val needsChecking = handlers.any { it !is ContainerHandler }
 	private val lastSizes = IntArray(this.handlers.size)
 	private var totalSize = 0
 	private val mappings = ArrayList<Mapping>()
 	private data class Mapping(val handler: IItemHandler, val slot: Int)
 
-	private fun check() {
+	init {
+		check(true)
+	}
+
+	private fun check(force: Boolean = false) {
+		if (!needsChecking && !force)
+			return
+
 		for ((i, handler) in handlers.withIndex()) {
 			var oldSize = lastSizes[i]