diff --git a/src/LibHac/Fs/Buffers/IBufferManager.cs b/src/LibHac/Fs/Buffers/IBufferManager.cs
index 63e03365..83788f48 100644
--- a/src/LibHac/Fs/Buffers/IBufferManager.cs
+++ b/src/LibHac/Fs/Buffers/IBufferManager.cs
@@ -1,7 +1,7 @@
 using System;
 
 using Buffer = LibHac.Mem.Buffer;
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 // ReSharper disable once CheckNamespace
 namespace LibHac.Fs;
diff --git a/src/LibHac/FsSystem/BufferedStorage.cs b/src/LibHac/FsSystem/BufferedStorage.cs
index 153b91dd..09c7d97b 100644
--- a/src/LibHac/FsSystem/BufferedStorage.cs
+++ b/src/LibHac/FsSystem/BufferedStorage.cs
@@ -9,7 +9,7 @@ using LibHac.FsSystem.Buffers;
 using LibHac.Util;
 
 using Buffer = LibHac.Mem.Buffer;
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 namespace LibHac.FsSystem;
 
diff --git a/src/LibHac/FsSystem/Buffers/FileSystemBufferManager.cs b/src/LibHac/FsSystem/Buffers/FileSystemBufferManager.cs
index 4c1b851a..f3acf25c 100644
--- a/src/LibHac/FsSystem/Buffers/FileSystemBufferManager.cs
+++ b/src/LibHac/FsSystem/Buffers/FileSystemBufferManager.cs
@@ -9,7 +9,7 @@ using LibHac.Os;
 using LibHac.Util;
 
 using Buffer = LibHac.Mem.Buffer;
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 // ReSharper disable once CheckNamespace
 namespace LibHac.FsSystem;
@@ -17,6 +17,7 @@ namespace LibHac.FsSystem;
 /// <summary>
 /// An <see cref="IBufferManager"/> that uses a <see cref="FileSystemBuddyHeap"/> as an allocator.
 /// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public class FileSystemBufferManager : IBufferManager
 {
     private class CacheHandleTable : IDisposable
diff --git a/src/LibHac/FsSystem/CompressedStorage.cs b/src/LibHac/FsSystem/CompressedStorage.cs
index 51392f20..13443ad9 100644
--- a/src/LibHac/FsSystem/CompressedStorage.cs
+++ b/src/LibHac/FsSystem/CompressedStorage.cs
@@ -6,7 +6,7 @@ using LibHac.FsSystem.Impl;
 using LibHac.Os;
 
 using Buffer = LibHac.Mem.Buffer;
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 namespace LibHac.FsSystem;
 
diff --git a/src/LibHac/FsSystem/Impl/BlockCacheManager.cs b/src/LibHac/FsSystem/Impl/BlockCacheManager.cs
index 237f07ef..51a24273 100644
--- a/src/LibHac/FsSystem/Impl/BlockCacheManager.cs
+++ b/src/LibHac/FsSystem/Impl/BlockCacheManager.cs
@@ -3,7 +3,7 @@ using LibHac.Diag;
 using LibHac.Fs;
 
 using Buffer = LibHac.Mem.Buffer;
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 namespace LibHac.FsSystem.Impl;
 
diff --git a/tests/LibHac.Tests/FsSystem/FileSystemBufferManagerTests.cs b/tests/LibHac.Tests/FsSystem/FileSystemBufferManagerTests.cs
index 55df93e7..cad8dad0 100644
--- a/tests/LibHac.Tests/FsSystem/FileSystemBufferManagerTests.cs
+++ b/tests/LibHac.Tests/FsSystem/FileSystemBufferManagerTests.cs
@@ -3,7 +3,7 @@ using LibHac.FsSystem;
 using LibHac.Mem;
 using Xunit;
 
-using CacheHandle = System.Int64;
+using CacheHandle = System.UInt64;
 
 namespace LibHac.Tests.FsSystem;