diff --git a/LibHac/Crypto.cs b/LibHac/Crypto.cs
index 6c8551a8..db1f0932 100644
--- a/LibHac/Crypto.cs
+++ b/LibHac/Crypto.cs
@@ -21,6 +21,14 @@ namespace LibHac
             return comp;
         }
 
+        public static byte[] ComputeSha256(byte[] data, int offset, int count)
+        {
+            using (SHA256 sha = SHA256.Create())
+            {
+                return sha.ComputeHash(data, offset, count);
+            }
+        }
+
         public static void DecryptEcb(byte[] key, byte[] src, int srcIndex, byte[] dest, int destIndex, int length)
         {
             using (Aes aes = Aes.Create())
diff --git a/LibHac/Save/Header.cs b/LibHac/Save/Header.cs
index 17afa2f8..70da2619 100644
--- a/LibHac/Save/Header.cs
+++ b/LibHac/Save/Header.cs
@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using LibHac.Streams;
 
 namespace LibHac.Save
 {
@@ -24,13 +25,17 @@ namespace LibHac.Save
         public byte[] DuplexMasterA { get; }
         public byte[] DuplexMasterB { get; }
 
+        public Stream MasterHash { get; }
+
         public Validity SignatureValidity { get; }
         public Validity HeaderHashValidity { get; }
 
         public byte[] Data { get; }
 
-        public Header(Keyset keyset, BinaryReader reader)
+        public Header(Keyset keyset, SharedStreamSource streamSource)
         {
+            var reader = new BinaryReader(streamSource.CreateStream());
+
             reader.BaseStream.Position = 0;
             Data = reader.ReadBytes(0x4000);
             reader.BaseStream.Position = 0;
@@ -65,6 +70,8 @@ namespace LibHac.Save
             reader.BaseStream.Position = Layout.IvfcMasterHashOffsetB;
             MasterHashB = reader.ReadBytes((int)Layout.IvfcMasterHashSize);
 
+            MasterHash = streamSource.CreateStream(Layout.IvfcMasterHashOffsetA, Layout.IvfcMasterHashSize);
+
             reader.BaseStream.Position = Layout.DuplexMasterOffsetA;
             DuplexMasterA = reader.ReadBytes((int)Layout.DuplexMasterSize);
             reader.BaseStream.Position = Layout.DuplexMasterOffsetB;
diff --git a/LibHac/Save/Savefile.cs b/LibHac/Save/Savefile.cs
index 3ab2f999..172bfe49 100644
--- a/LibHac/Save/Savefile.cs
+++ b/LibHac/Save/Savefile.cs
@@ -28,33 +28,30 @@ namespace LibHac.Save
         {
             SavefileSource = new SharedStreamSource(file);
 
-            using (var reader = new BinaryReader(SavefileSource.CreateStream(), Encoding.Default, true))
-            {
-                Header = new Header(keyset, reader);
-                FsLayout layout = Header.Layout;
+            Header = new Header(keyset, SavefileSource);
+            FsLayout layout = Header.Layout;
 
-                DataRemapStorage = new RemapStorage(SavefileSource.CreateStream(layout.FileMapDataOffset, layout.FileMapDataSize),
-                        Header.FileRemap, Header.FileMapEntries);
+            DataRemapStorage = new RemapStorage(SavefileSource.CreateStream(layout.FileMapDataOffset, layout.FileMapDataSize),
+                    Header.FileRemap, Header.FileMapEntries);
 
-                DuplexData = InitDuplexStream(DataRemapStorage, Header);
+            DuplexData = InitDuplexStream(DataRemapStorage, Header);
 
-                MetaRemapStorage = new RemapStorage(DuplexData, Header.MetaRemap, Header.MetaMapEntries);
+            MetaRemapStorage = new RemapStorage(DuplexData, Header.MetaRemap, Header.MetaMapEntries);
 
-                Stream journalTable = MetaRemapStorage.OpenStream(layout.JournalTableOffset, layout.JournalTableSize);
+            Stream journalTable = MetaRemapStorage.OpenStream(layout.JournalTableOffset, layout.JournalTableSize);
 
-                MappingEntry[] journalMap = JournalStream.ReadMappingEntries(journalTable, Header.Journal.MainDataBlockCount);
+            MappingEntry[] journalMap = JournalStream.ReadMappingEntries(journalTable, Header.Journal.MainDataBlockCount);
 
-                Stream journalData = DataRemapStorage.OpenStream(layout.JournalDataOffset,
-                    layout.JournalDataSizeB + layout.SizeReservedArea);
-                var journalStream = new JournalStream(journalData, journalMap, (int)Header.Journal.BlockSize);
-                JournalStreamSource = new SharedStreamSource(journalStream);
+            Stream journalData = DataRemapStorage.OpenStream(layout.JournalDataOffset,
+                layout.JournalDataSizeB + layout.SizeReservedArea);
+            var journalStream = new JournalStream(journalData, journalMap, (int)Header.Journal.BlockSize);
+            JournalStreamSource = new SharedStreamSource(journalStream);
 
-                IvfcStream = InitIvfcStream(integrityCheckLevel);
+            IvfcStream = InitIvfcStream(integrityCheckLevel);
 
-                SaveFs = new SaveFs(IvfcStream, MetaRemapStorage.OpenStream(layout.FatOffset, layout.FatSize), Header.Save);
+            SaveFs = new SaveFs(IvfcStream, MetaRemapStorage.OpenStream(layout.FatOffset, layout.FatSize), Header.Save);
 
-                IvfcStreamSource = new SharedStreamSource(IvfcStream);
-            }
+            IvfcStreamSource = new SharedStreamSource(IvfcStream);
         }
 
         private static LayeredDuplexFs InitDuplexStream(RemapStorage baseStorage, Header header)
@@ -95,7 +92,7 @@ namespace LibHac.Save
 
             initInfo[0] = new IntegrityVerificationInfo
             {
-                Data = new MemoryStream(Header.MasterHashA),
+                Data = Header.MasterHash,
                 BlockSize = 0,
                 Type = IntegrityStreamType.Save
             };
@@ -132,18 +129,28 @@ namespace LibHac.Save
 
         public bool FileExists(string filename) => SaveFs.FileExists(filename);
 
-        public bool SignHeader(Keyset keyset)
+        public bool CommitHeader(Keyset keyset)
         {
+            SharedStream headerStream = SavefileSource.CreateStream();
+
+            var hashData = new byte[0x3d00];
+
+            headerStream.Position = 0x300;
+            headerStream.Read(hashData, 0, hashData.Length);
+
+            byte[] hash = Crypto.ComputeSha256(hashData, 0, hashData.Length);
+            headerStream.Position = 0x108;
+            headerStream.Write(hash, 0, hash.Length);
+
             if (keyset.SaveMacKey.IsEmpty()) return false;
 
-            var data = new byte[0x200];
+            var cmacData = new byte[0x200];
             var cmac = new byte[0x10];
 
-            SharedStream headerStream = SavefileSource.CreateStream();
             headerStream.Position = 0x100;
-            headerStream.Read(data, 0, 0x200);
+            headerStream.Read(cmacData, 0, 0x200);
 
-            Crypto.CalculateAesCmac(keyset.SaveMacKey, data, 0, cmac, 0, 0x200);
+            Crypto.CalculateAesCmac(keyset.SaveMacKey, cmacData, 0, cmac, 0, 0x200);
 
             headerStream.Position = 0;
             headerStream.Write(cmac, 0, 0x10);
diff --git a/hactoolnet/ProcessSave.cs b/hactoolnet/ProcessSave.cs
index dce56572..3fd3f551 100644
--- a/hactoolnet/ProcessSave.cs
+++ b/hactoolnet/ProcessSave.cs
@@ -73,7 +73,7 @@ namespace hactoolnet
 
                 if (ctx.Options.SignSave)
                 {
-                    if (save.SignHeader(ctx.Keyset))
+                    if (save.CommitHeader(ctx.Keyset))
                     {
                         ctx.Logger.LogMessage("Successfully signed save file");
                     }