diff --git a/src/Filter.cs b/src/Filter.cs
index f841c39..94f5ee9 100644
--- a/src/Filter.cs
+++ b/src/Filter.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using MoonTools.ECS.Collections;
 
 namespace MoonTools.ECS
 {
@@ -8,7 +9,7 @@ namespace MoonTools.ECS
 		internal FilterSignature Signature;
 		private FilterStorage FilterStorage;
 
-		internal Filter(FilterStorage filterStorage, HashSet<int> included, HashSet<int> excluded)
+		internal Filter(FilterStorage filterStorage, IndexableSet<int> included, IndexableSet<int> excluded)
 		{
 			FilterStorage = filterStorage;
 			Signature = new FilterSignature(included, excluded);
diff --git a/src/FilterBuilder.cs b/src/FilterBuilder.cs
index ed1562e..8a8a6d1 100644
--- a/src/FilterBuilder.cs
+++ b/src/FilterBuilder.cs
@@ -1,5 +1,4 @@
-using System;
-using System.Collections.Generic;
+using MoonTools.ECS.Collections;
 
 namespace MoonTools.ECS
 {
@@ -7,18 +6,18 @@ namespace MoonTools.ECS
 	{
 		private TypeIndices ComponentTypeIndices;
 		private FilterStorage FilterStorage;
-		private HashSet<int> Included;
-		private HashSet<int> Excluded;
+		private IndexableSet<int> Included;
+		private IndexableSet<int> Excluded;
 
 		internal FilterBuilder(FilterStorage filterStorage, TypeIndices componentTypeIndices)
 		{
 			FilterStorage = filterStorage;
 			ComponentTypeIndices = componentTypeIndices;
-			Included = new HashSet<int>();
-			Excluded = new HashSet<int>();
+			Included = new IndexableSet<int>();
+			Excluded = new IndexableSet<int>();
 		}
 
-		private FilterBuilder(FilterStorage filterStorage, TypeIndices componentTypeIndices, HashSet<int> included, HashSet<int> excluded)
+		private FilterBuilder(FilterStorage filterStorage, TypeIndices componentTypeIndices, IndexableSet<int> included, IndexableSet<int> excluded)
 		{
 			FilterStorage = filterStorage;
 			ComponentTypeIndices = componentTypeIndices;
diff --git a/src/FilterSignature.cs b/src/FilterSignature.cs
index 3877391..f0eeaba 100644
--- a/src/FilterSignature.cs
+++ b/src/FilterSignature.cs
@@ -1,14 +1,15 @@
 using System;
 using System.Collections.Generic;
+using MoonTools.ECS.Collections;
 
 namespace MoonTools.ECS
 {
 	public struct FilterSignature : IEquatable<FilterSignature>
 	{
-		public readonly HashSet<int> Included;
-		public readonly HashSet<int> Excluded;
+		public readonly IndexableSet<int> Included;
+		public readonly IndexableSet<int> Excluded;
 
-		public FilterSignature(HashSet<int> included, HashSet<int> excluded)
+		public FilterSignature(IndexableSet<int> included, IndexableSet<int> excluded)
 		{
 			Included = included;
 			Excluded = excluded;
diff --git a/src/FilterStorage.cs b/src/FilterStorage.cs
index fc7718f..163751e 100644
--- a/src/FilterStorage.cs
+++ b/src/FilterStorage.cs
@@ -20,7 +20,7 @@ namespace MoonTools.ECS
 			ComponentTypeIndices = componentTypeIndices;
 		}
 
-		public Filter CreateFilter(HashSet<int> included, HashSet<int> excluded)
+		public Filter CreateFilter(IndexableSet<int> included, IndexableSet<int> excluded)
 		{
 			var filterSignature = new FilterSignature(included, excluded);
 			if (!filterSignatureToEntityIDs.ContainsKey(filterSignature))