diff --git a/src/main/kotlin/MultiSortedList.kt b/src/main/kotlin/MultiSortedList.kt
index 8eaa4f1..194d4eb 100644
--- a/src/main/kotlin/MultiSortedList.kt
+++ b/src/main/kotlin/MultiSortedList.kt
@@ -1,20 +1,36 @@
 import java.util.*
 import kotlin.Comparator
+import kotlin.collections.ArrayList
 
 class MultiSortedList<E> constructor(
     underlying: MutableList<E>,
+    generator: () -> MutableList<E>,
     comparator: Comparator<in E>,
     vararg extraComparators: Comparator<in E>
 ): SortedList<E>(underlying, comparator) {
     companion object {
         fun <T: Comparable<T>> ofComparable(
-            underlying: MutableList<T> = ArrayList(),
+            underlying: MutableList<T>,
+            generator: () -> MutableList<T> = ::ArrayList,
             comparator: Comparator<in T> = Comparator { a, b -> a.compareTo(b) },
             vararg extraComparators: Comparator<in T>
-        ) = MultiSortedList(underlying, comparator, *extraComparators)
+        ) = MultiSortedList(underlying, generator, comparator, *extraComparators)
+
+        fun <T: Comparable<T>> ofComparable(
+            generator: () -> MutableList<T> = ::ArrayList,
+            comparator: Comparator<in T> = Comparator { a, b -> a.compareTo(b) },
+            vararg extraComparators: Comparator<in T>
+        ) = MultiSortedList(generator(), generator, comparator, *extraComparators)
     }
 
-    private var extraLists = extraComparators.associateWith { SortedList(underlying.subList(0, underlying.size), it) }
+    constructor(generator: () -> MutableList<E>, comparator: Comparator<in E>, vararg extraComparators: Comparator<in E>):
+            this(generator(), generator, comparator, *extraComparators)
+
+    private var extraLists = extraComparators.associateWith {
+        val list = generator()
+        Collections.copy(list, underlying)
+        SortedList(list, it)
+    }
 
     override fun add(element: E): Boolean {
         extraLists.values.forEach {
diff --git a/src/main/kotlin/PortalManager.kt b/src/main/kotlin/PortalManager.kt
index a723046..68d9536 100644
--- a/src/main/kotlin/PortalManager.kt
+++ b/src/main/kotlin/PortalManager.kt
@@ -24,8 +24,8 @@ private const val DEFAULT_COOLDOWN_MIN = 5L
 class PortalManager(private val data: ConfigurationSection, private val config: () -> ConfigurationSection): Listener {
     private val players = PlayerMapper(data, PATH_DATA_PLAYERS)
     private val worlds = WorldMapper(data, PATH_DATA_WORLDS)
-    private var portals = MultiSortedList(ArrayList(), COMPARATOR_PORTAL_LOCATION_OWNER, COMPARATOR_PORTAL_UID, COMPARATOR_PORTAL_OWNER_NAME, COMPARATOR_PORTAL_LINKS)
-    private var invitations = MultiSortedList(ArrayList(), COMPARATOR_INVITE_RECIPIENT, COMPARATOR_INVITE_PORTAL)
+    private var portals = MultiSortedList(::ArrayList, COMPARATOR_PORTAL_LOCATION_OWNER, COMPARATOR_PORTAL_UID, COMPARATOR_PORTAL_OWNER_NAME, COMPARATOR_PORTAL_LINKS)
+    private var invitations = MultiSortedList(::ArrayList, COMPARATOR_INVITE_RECIPIENT, COMPARATOR_INVITE_PORTAL)
 
     private val cooldowns = LinkedList<Pair<OfflinePlayer, Long>>()
     private val cooldownsLookup = SortedList<OfflinePlayer>(ArrayList(), COMPARATOR_PLAYER)
@@ -92,7 +92,7 @@ class PortalManager(private val data: ConfigurationSection, private val config:
             if (portal.id >= nextUUID)
                 nextUUID = portal.id + 1UL
         }
-        portals = MultiSortedList(portalList, COMPARATOR_PORTAL_LOCATION_OWNER, COMPARATOR_PORTAL_UID)
+        portals = MultiSortedList(portalList, ::ArrayList, COMPARATOR_PORTAL_LOCATION_OWNER, COMPARATOR_PORTAL_UID)
 
         if(portals.isEmpty()) nextUUID = UUID(0, 0)
         else {
@@ -105,6 +105,7 @@ class PortalManager(private val data: ConfigurationSection, private val config:
 
         invitations = MultiSortedList(
             data.getStringList(PATH_DATA_INVITES).mapTo(ArrayList(), ::Invite),
+            ::ArrayList,
             COMPARATOR_INVITE_RECIPIENT,
             COMPARATOR_INVITE_PORTAL
         )