diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/container/CombinedContainer.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/container/CombinedContainer.kt
index 992139a7a..a7094db4a 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/container/CombinedContainer.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/container/CombinedContainer.kt
@@ -43,11 +43,11 @@ class CombinedContainer(containers: Stream<Pair<Container, Iterable<Int>>>) : IM
 		}
 	}
 
-	private val slots: List<Slot>
-	private val slotsMap: Map<Container, List<IContainerSlot>>
-	private val containers: Set<Container>
-	private val fullCoverage: List<Container>
-	private val notFullCoverage: Map<Container, List<IContainerSlot>>
+	private val slots: ImmutableList<Slot>
+	private val slotsMap: ImmutableMap<Container, List<IContainerSlot>>
+	private val containers: ImmutableSet<Container>
+	private val fullCoverage: ImmutableList<Container>
+	private val notFullCoverage: ImmutableMap<Container, List<IContainerSlot>>
 
 	init {
 		val list = ImmutableList.Builder<Slot>()