diff --git a/src/LibHac/Fs/Fsa/Registrar.cs b/src/LibHac/Fs/Fsa/Registrar.cs
index 1a2e06f0..5ac0b76a 100644
--- a/src/LibHac/Fs/Fsa/Registrar.cs
+++ b/src/LibHac/Fs/Fsa/Registrar.cs
@@ -1,7 +1,7 @@
 using System;
 using LibHac.Common;
+using LibHac.Diag;
 using LibHac.Fs.Impl;
-using LibHac.Util;
 
 namespace LibHac.Fs.Fsa;
 
@@ -15,12 +15,93 @@ public interface ISaveDataAttributeGetter : IDisposable
     Result GetSaveDataAttribute(out SaveDataAttribute attribute);
 }
 
+public interface IUnmountHookInvoker : IDisposable
+{
+    void Invoke();
+}
+
 /// <summary>
 /// Contains functions for registering and unregistering mounted <see cref="IFileSystem"/>s.
 /// </summary>
-/// <remarks>Based on FS 12.1.0 (nnSdk 12.3.1)</remarks>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
 public static class Registrar
 {
+    private class UnmountHookFileSystem : IFileSystem
+    {
+        private UniqueRef<IFileSystem> _fileSystem;
+        private UniqueRef<IUnmountHookInvoker> _unmountHookInvoker;
+
+        public UnmountHookFileSystem(ref UniqueRef<IFileSystem> fileSystem,
+            ref UniqueRef<IUnmountHookInvoker> unmountHookInvoker)
+        {
+            _fileSystem = new UniqueRef<IFileSystem>(ref fileSystem);
+            _unmountHookInvoker = new UniqueRef<IUnmountHookInvoker>(ref unmountHookInvoker);
+        }
+
+        public override void Dispose()
+        {
+            if (_unmountHookInvoker.HasValue)
+                _unmountHookInvoker.Get.Invoke();
+
+            _unmountHookInvoker.Destroy();
+            _fileSystem.Destroy();
+
+            base.Dispose();
+        }
+
+        protected override Result DoCreateFile(in Path path, long size, CreateFileOptions option) =>
+            _fileSystem.Get.CreateFile(in path, size, option);
+
+        protected override Result DoDeleteFile(in Path path) => _fileSystem.Get.DeleteFile(in path);
+
+        protected override Result DoCreateDirectory(in Path path) => _fileSystem.Get.CreateDirectory(in path);
+
+        protected override Result DoDeleteDirectory(in Path path) => _fileSystem.Get.DeleteDirectory(in path);
+
+        protected override Result DoDeleteDirectoryRecursively(in Path path) =>
+            _fileSystem.Get.DeleteDirectoryRecursively(in path);
+
+        protected override Result DoCleanDirectoryRecursively(in Path path) =>
+            _fileSystem.Get.CleanDirectoryRecursively(in path);
+
+        protected override Result DoRenameFile(in Path currentPath, in Path newPath) =>
+            _fileSystem.Get.RenameFile(in currentPath, in newPath);
+
+        protected override Result DoRenameDirectory(in Path currentPath, in Path newPath) =>
+            _fileSystem.Get.RenameDirectory(in currentPath, in newPath);
+
+        protected override Result DoGetEntryType(out DirectoryEntryType entryType, in Path path) =>
+            _fileSystem.Get.GetEntryType(out entryType, in path);
+
+        protected override Result DoGetFreeSpaceSize(out long freeSpace, in Path path) =>
+            _fileSystem.Get.GetFreeSpaceSize(out freeSpace, in path);
+
+        protected override Result DoGetTotalSpaceSize(out long totalSpace, in Path path) =>
+            _fileSystem.Get.GetTotalSpaceSize(out totalSpace, in path);
+
+        protected override Result DoOpenFile(ref UniqueRef<IFile> outFile, in Path path, OpenMode mode) =>
+            _fileSystem.Get.OpenFile(ref outFile, in path, mode);
+
+        protected override Result DoOpenDirectory(ref UniqueRef<IDirectory> outDirectory, in Path path,
+            OpenDirectoryMode mode) =>
+            _fileSystem.Get.OpenDirectory(ref outDirectory, in path, mode);
+
+        protected override Result DoCommit() => _fileSystem.Get.Commit();
+
+        protected override Result DoCommitProvisionally(long counter) =>
+            _fileSystem.Get.CommitProvisionally(counter);
+
+        protected override Result DoRollback() => _fileSystem.Get.Rollback();
+
+        protected override Result DoFlush() => _fileSystem.Get.Flush();
+
+        protected override Result DoGetFileTimeStampRaw(out FileTimeStampRaw timeStamp, in Path path) =>
+            _fileSystem.Get.GetFileTimeStampRaw(out timeStamp, in path);
+
+        protected override Result DoQueryEntry(Span<byte> outBuffer, ReadOnlySpan<byte> inBuffer, QueryId queryId,
+            in Path path) => _fileSystem.Get.QueryEntry(outBuffer, inBuffer, queryId, in path);
+    }
+
     public static Result Register(this FileSystemClient fs, U8Span name, ref UniqueRef<IFileSystem> fileSystem)
     {
         using var attributeGetter = new UniqueRef<ISaveDataAttributeGetter>();
@@ -51,12 +132,28 @@ public static class Registrar
 
     public static Result Register(this FileSystemClient fs, U8Span name, IMultiCommitTarget multiCommitTarget,
         ref UniqueRef<IFileSystem> fileSystem, ref UniqueRef<ICommonMountNameGenerator> mountNameGenerator,
-        bool useDataCache, bool usePathCache)
+        bool useDataCache, IStorage storageForPurgeFileDataCache, bool usePathCache)
+    {
+        using var unmountHookInvoker = new UniqueRef<IUnmountHookInvoker>();
+        using var attributeGetter = new UniqueRef<ISaveDataAttributeGetter>();
+
+        Result rc = Register(fs, name, multiCommitTarget, ref fileSystem, ref mountNameGenerator,
+            ref attributeGetter.Ref(), useDataCache, storageForPurgeFileDataCache, usePathCache,
+            ref unmountHookInvoker.Ref());
+        if (rc.IsFailure()) return rc.Miss();
+
+        return Result.Success;
+    }
+
+    public static Result Register(this FileSystemClient fs, U8Span name, IMultiCommitTarget multiCommitTarget,
+        ref UniqueRef<IFileSystem> fileSystem, ref UniqueRef<ICommonMountNameGenerator> mountNameGenerator,
+        bool useDataCache, IStorage storageForPurgeFileDataCache, bool usePathCache,
+        ref UniqueRef<IUnmountHookInvoker> unmountHook)
     {
         using var attributeGetter = new UniqueRef<ISaveDataAttributeGetter>();
 
         Result rc = Register(fs, name, multiCommitTarget, ref fileSystem, ref mountNameGenerator,
-            ref attributeGetter.Ref(), useDataCache, usePathCache, new Optional<Ncm.DataId>());
+            ref attributeGetter.Ref(), useDataCache, storageForPurgeFileDataCache, usePathCache, ref unmountHook);
         if (rc.IsFailure()) return rc.Miss();
 
         return Result.Success;
@@ -64,12 +161,14 @@ public static class Registrar
 
     public static Result Register(this FileSystemClient fs, U8Span name, IMultiCommitTarget multiCommitTarget,
         ref UniqueRef<IFileSystem> fileSystem, ref UniqueRef<ICommonMountNameGenerator> mountNameGenerator,
-        bool useDataCache, bool usePathCache, Optional<Ncm.DataId> dataId)
+        ref UniqueRef<ISaveDataAttributeGetter> saveAttributeGetter, bool useDataCache,
+        IStorage storageForPurgeFileDataCache, bool usePathCache)
     {
-        using var attributeGetter = new UniqueRef<ISaveDataAttributeGetter>();
+        using var unmountHookInvoker = new UniqueRef<IUnmountHookInvoker>();
 
         Result rc = Register(fs, name, multiCommitTarget, ref fileSystem, ref mountNameGenerator,
-            ref attributeGetter.Ref(), useDataCache, usePathCache, dataId);
+            ref saveAttributeGetter, useDataCache, storageForPurgeFileDataCache, usePathCache,
+            ref unmountHookInvoker.Ref());
         if (rc.IsFailure()) return rc.Miss();
 
         return Result.Success;
@@ -77,29 +176,29 @@ public static class Registrar
 
     public static Result Register(this FileSystemClient fs, U8Span name, IMultiCommitTarget multiCommitTarget,
         ref UniqueRef<IFileSystem> fileSystem, ref UniqueRef<ICommonMountNameGenerator> mountNameGenerator,
-        ref UniqueRef<ISaveDataAttributeGetter> saveAttributeGetter, bool useDataCache, bool usePathCache)
+        ref UniqueRef<ISaveDataAttributeGetter> saveAttributeGetter, bool useDataCache,
+        IStorage storageForPurgeFileDataCache, bool usePathCache, ref UniqueRef<IUnmountHookInvoker> unmountHook)
     {
-        Result rc = Register(fs, name, multiCommitTarget, ref fileSystem, ref mountNameGenerator,
-            ref saveAttributeGetter, useDataCache, usePathCache, new Optional<Ncm.DataId>());
-        if (rc.IsFailure()) return rc.Miss();
+        if (useDataCache)
+            Assert.SdkAssert(storageForPurgeFileDataCache is not null);
 
-        return Result.Success;
-    }
+        using (var unmountHookFileSystem =
+               new UniqueRef<UnmountHookFileSystem>(new UnmountHookFileSystem(ref fileSystem, ref unmountHook)))
+        {
+            fileSystem.Set(ref unmountHookFileSystem.Ref());
+        }
+
+        if (!fileSystem.HasValue)
+            return ResultFs.AllocationMemoryFailedInRegisterB.Log();
 
-    public static Result Register(this FileSystemClient fs, U8Span name, IMultiCommitTarget multiCommitTarget,
-        ref UniqueRef<IFileSystem> fileSystem, ref UniqueRef<ICommonMountNameGenerator> mountNameGenerator,
-        ref UniqueRef<ISaveDataAttributeGetter> saveAttributeGetter, bool useDataCache, bool usePathCache,
-        Optional<Ncm.DataId> dataId)
-    {
         using var accessor = new UniqueRef<FileSystemAccessor>(new FileSystemAccessor(fs.Hos, name,
             multiCommitTarget, ref fileSystem, ref mountNameGenerator, ref saveAttributeGetter));
 
         if (!accessor.HasValue)
             return ResultFs.AllocationMemoryFailedInRegisterB.Log();
 
-        // accessor.Get.SetFileDataCacheAttachable(useDataCache);
+        accessor.Get.SetFileDataCacheAttachable(useDataCache, storageForPurgeFileDataCache);
         accessor.Get.SetPathBasedFileDataCacheAttachable(usePathCache);
-        // accessor.Get.SetDataId(dataId);
 
         Result rc = fs.Impl.Register(ref accessor.Ref());
         if (rc.IsFailure()) return rc.Miss();
diff --git a/src/LibHac/Fs/Shim/SaveData.cs b/src/LibHac/Fs/Shim/SaveData.cs
index 704f58d6..9a11a4cd 100644
--- a/src/LibHac/Fs/Shim/SaveData.cs
+++ b/src/LibHac/Fs/Shim/SaveData.cs
@@ -50,7 +50,7 @@ public static class SaveData
         using var mountNameGenerator = new UniqueRef<ICommonMountNameGenerator>();
 
         rc = fs.Fs.Register(mountName, fileSystemAdapterRaw, ref fileSystemAdapter.Ref(),
-            ref mountNameGenerator.Ref(), false, true);
+            ref mountNameGenerator.Ref(), false, null, true);
         if (rc.IsFailure()) return rc.Miss();
 
         return Result.Success;
@@ -291,4 +291,4 @@ public static class SaveData
 
         return rc;
     }
-}
+}
\ No newline at end of file
diff --git a/src/LibHac/Fs/Shim/SystemSaveData.cs b/src/LibHac/Fs/Shim/SystemSaveData.cs
index c55c85c0..3de0cab7 100644
--- a/src/LibHac/Fs/Shim/SystemSaveData.cs
+++ b/src/LibHac/Fs/Shim/SystemSaveData.cs
@@ -87,7 +87,7 @@ public static class SystemSaveData
             {
                 using var mountNameGenerator = new UniqueRef<ICommonMountNameGenerator>();
                 return fs.Register(mountName, fileSystemAdapterRaw, ref fileSystemAdapter.Ref(),
-                    ref mountNameGenerator.Ref(), false, false);
+                    ref mountNameGenerator.Ref(), false, null, false);
             }
             else
             {
@@ -95,4 +95,4 @@ public static class SystemSaveData
             }
         }
     }
-}
+}
\ No newline at end of file