diff --git a/src/LibHac/FsSrv/FileSystemServer.cs b/src/LibHac/FsSrv/FileSystemServer.cs
index 1c6adecd..527ef384 100644
--- a/src/LibHac/FsSrv/FileSystemServer.cs
+++ b/src/LibHac/FsSrv/FileSystemServer.cs
@@ -29,6 +29,7 @@ internal struct FileSystemServerGlobals
     public ProgramRegistryImplGlobals ProgramRegistryImpl;
     public DeviceEventSimulatorGlobals DeviceEventSimulator;
     public AccessControlGlobals AccessControl;
+    public ProgramInfoGlobals ProgramInfo;
     public StorageDeviceManagerFactoryGlobals StorageDeviceManagerFactory;
     public SaveDataSharedFileStorageGlobals SaveDataSharedFileStorage;
     public MultiCommitManagerGlobals MultiCommitManager;
@@ -63,4 +64,4 @@ public readonly struct FileSystemServerImpl
     internal ref FileSystemServerGlobals Globals => ref FsSrv.Globals;
 
     internal FileSystemServerImpl(FileSystemServer parentServer) => FsSrv = parentServer;
-}
+}
\ No newline at end of file
diff --git a/src/LibHac/FsSrv/Impl/ProgramInfo.cs b/src/LibHac/FsSrv/Impl/ProgramInfo.cs
new file mode 100644
index 00000000..70ad6f6d
--- /dev/null
+++ b/src/LibHac/FsSrv/Impl/ProgramInfo.cs
@@ -0,0 +1,120 @@
+using System;
+using LibHac.Common;
+using LibHac.Diag;
+using LibHac.Ncm;
+using LibHac.Os;
+
+namespace LibHac.FsSrv.Impl;
+
+public static class ProgramInfoGlobalMethods
+{
+    public static bool IsInitialProgram(this FileSystemServer fsSrv, ulong processId)
+    {
+        ref ProgramInfoGlobals g = ref fsSrv.Globals.ProgramInfo;
+        using (var guard = new InitializationGuard(ref g.InitialProcessIdRangeInitGuard, fsSrv.Globals.InitMutex))
+        {
+            if (!guard.IsInitialized)
+            {
+                // Todo: We have no kernel to call into, so use hardcoded values for now
+                g.InitialProcessIdMin = OsState.InitialProcessCountMin;
+                g.InitialProcessIdMax = OsState.InitialProcessCountMax;
+
+                Abort.DoAbortUnless(0 < g.InitialProcessIdMin && g.InitialProcessIdMin <= g.InitialProcessIdMax,
+                    "Invalid initial process ID range");
+            }
+        }
+
+        Abort.DoAbortUnless(g.InitialProcessIdMin != 0);
+
+        return g.InitialProcessIdMin <= processId && processId <= g.InitialProcessIdMax;
+    }
+
+    public static bool IsCurrentProcess(this FileSystemServer fsSrv, ulong processId)
+    {
+        ref ProgramInfoGlobals g = ref fsSrv.Globals.ProgramInfo;
+        using (var guard = new InitializationGuard(ref g.CurrentProcessIdInitGuard, fsSrv.Globals.InitMutex))
+        {
+            if (!guard.IsInitialized)
+            {
+                g.CurrentProcessId = fsSrv.Hos.Os.GetCurrentProcessId().Value;
+            }
+        }
+
+        return g.CurrentProcessId == processId;
+    }
+}
+
+internal struct ProgramInfoGlobals
+{
+    public nint CurrentProcessIdInitGuard;
+    public ulong CurrentProcessId;
+
+    public nint InitialProcessIdRangeInitGuard;
+    public ulong InitialProcessIdMin;
+    public ulong InitialProcessIdMax;
+
+    public nint ProgramInfoForInitialProcessInitGuard;
+    public ProgramInfo ProgramInfoForInitialProcess;
+}
+
+/// <summary>
+/// Contains the program ID, storage location and FS permissions of a running process.
+/// </summary>
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
+public class ProgramInfo
+{
+    private readonly ulong _processId;
+    public ProgramId ProgramId { get; }
+    public StorageId StorageId { get; }
+    public AccessControl AccessControl { get; }
+
+    public ulong ProgramIdValue => ProgramId.Value;
+
+    private ProgramInfo(FileSystemServer fsServer, ReadOnlySpan<byte> accessControlData,
+        ReadOnlySpan<byte> accessControlDescriptor)
+    {
+        _processId = 0;
+        AccessControl = new AccessControl(fsServer, accessControlData, accessControlDescriptor, ulong.MaxValue);
+        ProgramId = default;
+        StorageId = 0;
+    }
+
+    public ProgramInfo(FileSystemServer fsServer, ulong processId, ProgramId programId, StorageId storageId,
+        ReadOnlySpan<byte> accessControlData, ReadOnlySpan<byte> accessControlDescriptor)
+    {
+        _processId = processId;
+        AccessControl = new AccessControl(fsServer, accessControlData, accessControlDescriptor);
+        ProgramId = programId;
+        StorageId = storageId;
+    }
+
+    public bool Contains(ulong processId) => _processId == processId;
+
+    public static ProgramInfo GetProgramInfoForInitialProcess(FileSystemServer fsSrv)
+    {
+        ref ProgramInfoGlobals g = ref fsSrv.Globals.ProgramInfo;
+        using (var guard = new InitializationGuard(ref g.ProgramInfoForInitialProcessInitGuard, fsSrv.Globals.InitMutex))
+        {
+            if (!guard.IsInitialized)
+            {
+                g.ProgramInfoForInitialProcess = new ProgramInfo(fsSrv, InitialProcessAccessControlDataHeader,
+                    InitialProcessAccessControlDescriptor);
+            }
+        }
+
+        return g.ProgramInfoForInitialProcess;
+    }
+
+    private static ReadOnlySpan<byte> InitialProcessAccessControlDataHeader => new byte[]
+    {
+        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x1C, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0x1C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+    };
+
+    private static ReadOnlySpan<byte> InitialProcessAccessControlDescriptor => new byte[]
+    {
+        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
+    };
+}
\ No newline at end of file
diff --git a/src/LibHac/FsSrv/Impl/ProgramRegistryManager.cs b/src/LibHac/FsSrv/Impl/ProgramRegistryManager.cs
index 6e722f71..be69cc92 100644
--- a/src/LibHac/FsSrv/Impl/ProgramRegistryManager.cs
+++ b/src/LibHac/FsSrv/Impl/ProgramRegistryManager.cs
@@ -3,43 +3,31 @@ using System.Collections.Generic;
 using LibHac.Common;
 using LibHac.Fs;
 using LibHac.Ncm;
+using LibHac.Os;
 
 namespace LibHac.FsSrv.Impl;
 
 /// <summary>
 /// Handles adding, removing, and accessing <see cref="ProgramInfo"/> from the <see cref="ProgramRegistryImpl"/>.
 /// </summary>
-/// <remarks>Based on FS 10.0.0 (nnSdk 10.4.0)</remarks>
-internal class ProgramRegistryManager
+/// <remarks>Based on FS 13.1.0 (nnSdk 13.4.0)</remarks>
+internal class ProgramRegistryManager : IDisposable
 {
     // Note: FS keeps each ProgramInfo in a shared_ptr, but there aren't any non-memory resources
     // that need to be freed, so we use plain ProgramInfos
-    private LinkedList<ProgramInfo> ProgramInfoList { get; }
-    private FileSystemServer FsServer { get; }
+    private LinkedList<ProgramInfo> _programInfoList;
+    private SdkMutexType _mutex;
 
-    // Note: This variable is global in FS. It's moved to ProgramRegistryManager here because it
-    // relies on some state kept in FileSystemServer, and it's only used by ProgramRegistryManager
-    private ProgramInfo _programInfoForInitialProcess;
-    private readonly object _programInfoForInitialProcessGuard = new object();
+    private FileSystemServer _fsServer;
 
     public ProgramRegistryManager(FileSystemServer fsServer)
     {
-        ProgramInfoList = new LinkedList<ProgramInfo>();
-        FsServer = fsServer;
+        _programInfoList = new LinkedList<ProgramInfo>();
+        _mutex = new SdkMutexType();
+        _fsServer = fsServer;
     }
 
-    private ProgramInfo GetProgramInfoForInitialProcess()
-    {
-        if (_programInfoForInitialProcess == null)
-        {
-            lock (_programInfoForInitialProcessGuard)
-            {
-                _programInfoForInitialProcess ??= ProgramInfo.CreateProgramInfoForInitialProcess(FsServer);
-            }
-        }
-
-        return _programInfoForInitialProcess;
-    }
+    public void Dispose() { }
 
     /// <summary>
     /// Registers a program with information about that program in the program registry.
@@ -54,20 +42,19 @@ internal class ProgramRegistryManager
     public Result RegisterProgram(ulong processId, ProgramId programId, StorageId storageId,
         ReadOnlySpan<byte> accessControlData, ReadOnlySpan<byte> accessControlDescriptor)
     {
-        var programInfo = new ProgramInfo(FsServer, processId, programId, storageId, accessControlData,
+        var programInfo = new ProgramInfo(_fsServer, processId, programId, storageId, accessControlData,
             accessControlDescriptor);
 
-        lock (ProgramInfoList)
-        {
-            foreach (ProgramInfo info in ProgramInfoList)
-            {
-                if (info.Contains(processId))
-                    return ResultFs.InvalidArgument.Log();
-            }
+        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
 
-            ProgramInfoList.AddLast(programInfo);
-            return Result.Success;
+        foreach (ProgramInfo info in _programInfoList)
+        {
+            if (info.Contains(processId))
+                return ResultFs.InvalidArgument.Log();
         }
+
+        _programInfoList.AddLast(programInfo);
+        return Result.Success;
     }
 
     /// <summary>
@@ -78,19 +65,18 @@ internal class ProgramRegistryManager
     /// <see cref="ResultFs.InvalidArgument"/>: The process ID is not registered.</returns>
     public Result UnregisterProgram(ulong processId)
     {
-        lock (ProgramInfoList)
-        {
-            for (LinkedListNode<ProgramInfo> node = ProgramInfoList.First; node != null; node = node.Next)
-            {
-                if (node.Value.Contains(processId))
-                {
-                    ProgramInfoList.Remove(node);
-                    return Result.Success;
-                }
-            }
+        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
 
-            return ResultFs.InvalidArgument.Log();
+        for (LinkedListNode<ProgramInfo> node = _programInfoList.First; node != null; node = node.Next)
+        {
+            if (node.Value.Contains(processId))
+            {
+                _programInfoList.Remove(node);
+                return Result.Success;
+            }
         }
+
+        return ResultFs.InvalidArgument.Log();
     }
 
     /// <summary>
@@ -103,26 +89,25 @@ internal class ProgramRegistryManager
     /// <see cref="ResultFs.ProgramInfoNotFound"/>: The <see cref="ProgramInfo"/> was not found.</returns>
     public Result GetProgramInfo(out ProgramInfo programInfo, ulong processId)
     {
-        lock (ProgramInfoList)
+        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        if (_fsServer.IsInitialProgram(processId))
         {
-            if (ProgramInfo.IsInitialProgram(processId))
+            programInfo = ProgramInfo.GetProgramInfoForInitialProcess(_fsServer);
+            return Result.Success;
+        }
+
+        foreach (ProgramInfo info in _programInfoList)
+        {
+            if (info.Contains(processId))
             {
-                programInfo = GetProgramInfoForInitialProcess();
+                programInfo = info;
                 return Result.Success;
             }
-
-            foreach (ProgramInfo info in ProgramInfoList)
-            {
-                if (info.Contains(processId))
-                {
-                    programInfo = info;
-                    return Result.Success;
-                }
-            }
-
-            UnsafeHelpers.SkipParamInit(out programInfo);
-            return ResultFs.ProgramInfoNotFound.Log();
         }
+
+        UnsafeHelpers.SkipParamInit(out programInfo);
+        return ResultFs.ProgramInfoNotFound.Log();
     }
 
     /// <summary>
@@ -135,77 +120,18 @@ internal class ProgramRegistryManager
     /// <see cref="ResultFs.ProgramInfoNotFound"/>: The <see cref="ProgramInfo"/> was not found.</returns>
     public Result GetProgramInfoByProgramId(out ProgramInfo programInfo, ulong programId)
     {
-        lock (ProgramInfoList)
+        using ScopedLock<SdkMutexType> scopedLock = ScopedLock.Lock(ref _mutex);
+
+        foreach (ProgramInfo info in _programInfoList)
         {
-            foreach (ProgramInfo info in ProgramInfoList)
+            if (info.ProgramId.Value == programId)
             {
-                if (info.ProgramId.Value == programId)
-                {
-                    programInfo = info;
-                    return Result.Success;
-                }
+                programInfo = info;
+                return Result.Success;
             }
-
-            UnsafeHelpers.SkipParamInit(out programInfo);
-            return ResultFs.ProgramInfoNotFound.Log();
         }
+
+        UnsafeHelpers.SkipParamInit(out programInfo);
+        return ResultFs.ProgramInfoNotFound.Log();
     }
-}
-
-public class ProgramInfo
-{
-    private ulong ProcessId { get; }
-    public ProgramId ProgramId { get; }
-    public StorageId StorageId { get; }
-    public AccessControl AccessControl { get; }
-
-    public ulong ProgramIdValue => ProgramId.Value;
-
-    public ProgramInfo(FileSystemServer fsServer, ulong processId, ProgramId programId, StorageId storageId,
-        ReadOnlySpan<byte> accessControlData, ReadOnlySpan<byte> accessControlDescriptor)
-    {
-        ProcessId = processId;
-        AccessControl = new AccessControl(fsServer, accessControlData, accessControlDescriptor);
-        ProgramId = programId;
-        StorageId = storageId;
-    }
-
-    private ProgramInfo(FileSystemServer fsServer, ReadOnlySpan<byte> accessControlData,
-        ReadOnlySpan<byte> accessControlDescriptor)
-    {
-        ProcessId = 0;
-        AccessControl = new AccessControl(fsServer, accessControlData, accessControlDescriptor, ulong.MaxValue);
-        ProgramId = default;
-        StorageId = 0;
-    }
-
-    public bool Contains(ulong processId) => ProcessId == processId;
-
-    public static bool IsInitialProgram(ulong processId)
-    {
-        // Todo: We have no kernel to call into, so use hardcoded values for now
-        const int initialProcessIdLowerBound = 1;
-        const int initialProcessIdUpperBound = 0x50;
-
-        return initialProcessIdLowerBound <= processId && processId <= initialProcessIdUpperBound;
-    }
-
-    internal static ProgramInfo CreateProgramInfoForInitialProcess(FileSystemServer fsServer)
-    {
-        return new ProgramInfo(fsServer, InitialProcessAccessControlDataHeader,
-            InitialProcessAccessControlDescriptor);
-    }
-
-    private static ReadOnlySpan<byte> InitialProcessAccessControlDataHeader => new byte[]
-    {
-        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x1C, 0x00, 0x00, 0x00,
-        0x00, 0x00, 0x00, 0x00, 0x1C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
-    };
-
-    private static ReadOnlySpan<byte> InitialProcessAccessControlDescriptor => new byte[]
-    {
-        0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00,
-        0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00,
-        0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
-    };
-}
+}
\ No newline at end of file
diff --git a/src/LibHac/FsSrv/ProgramRegistryImpl.cs b/src/LibHac/FsSrv/ProgramRegistryImpl.cs
index 973714ce..fc7c3633 100644
--- a/src/LibHac/FsSrv/ProgramRegistryImpl.cs
+++ b/src/LibHac/FsSrv/ProgramRegistryImpl.cs
@@ -50,7 +50,7 @@ public class ProgramRegistryImpl : IProgramRegistry
     public Result RegisterProgram(ulong processId, ProgramId programId, StorageId storageId,
         InBuffer accessControlData, InBuffer accessControlDescriptor)
     {
-        if (!ProgramInfo.IsInitialProgram(_processId))
+        if (!_fsServer.IsInitialProgram(_processId))
             return ResultFs.PermissionDenied.Log();
 
         return Globals.ServiceImpl.RegisterProgramInfo(processId, programId, storageId, accessControlData.Buffer,
@@ -63,7 +63,7 @@ public class ProgramRegistryImpl : IProgramRegistry
     /// <inheritdoc cref="ProgramRegistryManager.UnregisterProgram" />
     public Result UnregisterProgram(ulong processId)
     {
-        if (!ProgramInfo.IsInitialProgram(_processId))
+        if (!_fsServer.IsInitialProgram(_processId))
             return ResultFs.PermissionDenied.Log();
 
         return Globals.ServiceImpl.UnregisterProgramInfo(processId);
@@ -91,4 +91,4 @@ public class ProgramRegistryImpl : IProgramRegistry
         _processId = processId;
         return Result.Success;
     }
-}
+}
\ No newline at end of file
diff --git a/src/LibHac/FsSrv/SaveDataFileSystemService.cs b/src/LibHac/FsSrv/SaveDataFileSystemService.cs
index bf148599..fb1287c6 100644
--- a/src/LibHac/FsSrv/SaveDataFileSystemService.cs
+++ b/src/LibHac/FsSrv/SaveDataFileSystemService.cs
@@ -517,7 +517,7 @@ internal class SaveDataFileSystemService : ISaveDataTransferCoreInterface, ISave
         // Only the FS process may delete the save indexer's save data.
         if (saveDataId == SaveData.SaveIndexerId)
         {
-            if (!IsCurrentProcess(_processId))
+            if (!_serviceImpl.FsServer.IsCurrentProcess(_processId))
                 return ResultFs.PermissionDenied.Log();
 
             actualSpaceId = spaceId;
@@ -2157,13 +2157,6 @@ internal class SaveDataFileSystemService : ISaveDataTransferCoreInterface, ISave
         return _serviceImpl.GetProgramInfo(out programInfo, _processId);
     }
 
-    private bool IsCurrentProcess(ulong processId)
-    {
-        ulong currentId = Hos.Os.GetCurrentProcessId().Value;
-
-        return processId == currentId;
-    }
-
     private SaveDataSpaceId ConvertToRealSpaceId(SaveDataSpaceId spaceId)
     {
         return spaceId == SaveDataSpaceId.ProperSystem || spaceId == SaveDataSpaceId.SafeMode
diff --git a/src/LibHac/Horizon.cs b/src/LibHac/Horizon.cs
index e1756c0f..1d58acb1 100644
--- a/src/LibHac/Horizon.cs
+++ b/src/LibHac/Horizon.cs
@@ -12,8 +12,6 @@ namespace LibHac;
 
 public class Horizon
 {
-    private const int InitialProcessCountMax = 0x50;
-
     internal ITickGenerator TickGenerator { get; }
     internal ServiceManager ServiceManager { get; }
     private HorizonClient LoaderClient { get; }
@@ -23,7 +21,7 @@ public class Horizon
 
     public Horizon(HorizonConfiguration config)
     {
-        _currentProcessId = InitialProcessCountMax;
+        _currentProcessId = OsState.InitialProcessCountMax + 1;
 
         TickGenerator = config.TickGenerator ?? new DefaultTickGenerator();
         ServiceManager = new ServiceManager();
@@ -35,7 +33,7 @@ public class Horizon
     {
         ulong processId = Interlocked.Increment(ref _currentInitialProcessId);
 
-        Abort.DoAbortUnless(processId <= InitialProcessCountMax, "Created too many privileged clients.");
+        Abort.DoAbortUnless(processId <= OsState.InitialProcessCountMax, "Created too many privileged clients.");
 
         // Todo: Register process with FS
 
@@ -82,4 +80,4 @@ public class Horizon
 
         return client;
     }
-}
+}
\ No newline at end of file
diff --git a/src/LibHac/Os/OsState.cs b/src/LibHac/Os/OsState.cs
index 3a1d27a5..1322c9db 100644
--- a/src/LibHac/Os/OsState.cs
+++ b/src/LibHac/Os/OsState.cs
@@ -5,6 +5,9 @@ namespace LibHac.Os;
 
 public class OsState : IDisposable
 {
+    internal const int InitialProcessCountMin = 1;
+    internal const int InitialProcessCountMax = 0x50;
+
     public OsStateImpl Impl => new OsStateImpl(this);
     internal HorizonClient Hos { get; }
     internal OsResourceManager ResourceManager { get; }
@@ -34,4 +37,4 @@ public readonly struct OsStateImpl
     internal HorizonClient Hos => Os.Hos;
 
     internal OsStateImpl(OsState parent) => Os = parent;
-}
+}
\ No newline at end of file