diff --git a/AssetStudio/CubismMoc.cs b/AssetStudio/CubismMoc.cs
index 3d93695..12e5d18 100644
--- a/AssetStudio/CubismMoc.cs
+++ b/AssetStudio/CubismMoc.cs
@@ -57,7 +57,7 @@ namespace AssetStudio
             }
             isBigEndian = BitConverter.ToBoolean(modelData, 5);
 
-            var modelDataSpan = modelData.AsSpan();
+            var modelDataSpan = new ReadOnlySpan<byte>(modelData, 0, modelDataSize);
             //offsets
             var countInfoTableOffset = (int)modelDataSpan.ReadUInt32(64, isBigEndian);
             var canvasInfoOffset = (int)modelDataSpan.ReadUInt32(68, isBigEndian);
@@ -74,8 +74,8 @@ namespace AssetStudio
             //model
             PartCount = modelDataSpan.ReadUInt32(countInfoTableOffset, isBigEndian);
             ParamCount = modelDataSpan.ReadUInt32(countInfoTableOffset + 20, isBigEndian);
-            PartNames = ReadMocStrings(modelData, (int)partIdsOffset, (int)PartCount);
-            ParamNames = ReadMocStrings(modelData, (int)parameterIdsOffset, (int)ParamCount);
+            PartNames = ReadMocStrings(modelDataSpan, (int)partIdsOffset, (int)PartCount);
+            ParamNames = ReadMocStrings(modelDataSpan, (int)parameterIdsOffset, (int)ParamCount);
         }
 
         public void SaveMoc3(string savePath)
@@ -102,7 +102,7 @@ namespace AssetStudio
             }
         }
 
-        private static HashSet<string> ReadMocStrings(Span<byte> data, int index, int count)
+        private static HashSet<string> ReadMocStrings(ReadOnlySpan<byte> data, int index, int count)
         {
             const int strLen = 64;
             var strHashSet = new HashSet<string>();
diff --git a/AssetStudio/EndianSpanReader.cs b/AssetStudio/EndianSpanReader.cs
index 622848e..2657005 100644
--- a/AssetStudio/EndianSpanReader.cs
+++ b/AssetStudio/EndianSpanReader.cs
@@ -8,10 +8,10 @@ namespace AssetStudio
     {
         public static uint ReadUInt32(this Span<byte> data, int start, bool isBigEndian)
         {
-            return SpanToUInt32(data, start, isBigEndian);
+            return ReadUInt32((ReadOnlySpan<byte>)data, start, isBigEndian);
         }
 
-        public static uint SpanToUInt32(Span<byte> data, int start, bool isBigEndian)
+        public static uint ReadUInt32(this ReadOnlySpan<byte> data, int start, bool isBigEndian)
         {
             return isBigEndian
                 ? BinaryPrimitives.ReadUInt32BigEndian(data.Slice(start))
@@ -20,10 +20,10 @@ namespace AssetStudio
 
         public static long ReadUInt16(this Span<byte> data, int start, bool isBigEndian)
         {
-            return SpanToUInt16(data, start, isBigEndian);
+            return ReadUInt16((ReadOnlySpan<byte>)data, start, isBigEndian);
         }
 
-        public static uint SpanToUInt16(Span<byte> data, int start, bool isBigEndian)
+        public static uint ReadUInt16(this ReadOnlySpan<byte> data, int start, bool isBigEndian)
         {
             return isBigEndian
                 ? BinaryPrimitives.ReadUInt16BigEndian(data.Slice(start))
@@ -32,10 +32,10 @@ namespace AssetStudio
 
         public static long ReadInt64(this Span<byte> data, int start, bool isBigEndian)
         {
-            return SpanToInt64(data, start, isBigEndian);
+            return ReadInt64((ReadOnlySpan<byte>)data, start, isBigEndian);
         }
 
-        public static long SpanToInt64(Span<byte> data, int start, bool isBigEndian)
+        public static long ReadInt64(this ReadOnlySpan<byte> data, int start, bool isBigEndian)
         {
             return isBigEndian
                 ? BinaryPrimitives.ReadInt64BigEndian(data.Slice(start))
@@ -44,20 +44,20 @@ namespace AssetStudio
 
         public static float ReadSingle(this Span<byte> data, int start, bool isBigEndian)
         {
-            return SpanToSingle(data, start, isBigEndian);
+            return ReadSingle((ReadOnlySpan<byte>)data, start, isBigEndian);
         }
 
 #if NETFRAMEWORK
-        public static float SpanToSingle(Span<byte> data, int start, bool isBigEndian)
+        public static float ReadSingle(this ReadOnlySpan<byte> data, int start, bool isBigEndian)
         {
-            var bytes = data.Slice(start, 4);
+            var bytes = data.Slice(start, 4).ToArray();
             if ((isBigEndian && BitConverter.IsLittleEndian) || (!isBigEndian && !BitConverter.IsLittleEndian))
-                bytes.Reverse();
+                bytes.AsSpan().Reverse();
 
-            return BitConverter.ToSingle(bytes.ToArray(), 0);
+            return BitConverter.ToSingle(bytes, 0);
         }
 #else
-        public static float SpanToSingle(Span<byte> data, int start, bool isBigEndian)
+        public static float ReadSingle(this ReadOnlySpan<byte> data, int start, bool isBigEndian)
         {
             return isBigEndian
                 ? BinaryPrimitives.ReadSingleBigEndian(data[start..])
@@ -66,6 +66,11 @@ namespace AssetStudio
 #endif
 
         public static string ReadStringToNull(this Span<byte> data, int maxLength = 32767)
+        {
+            return ReadStringToNull((ReadOnlySpan<byte>)data, maxLength);
+        }
+
+        public static string ReadStringToNull(this ReadOnlySpan<byte> data, int maxLength = 32767)
         {
             Span<byte> bytes = stackalloc byte[maxLength];
             var count = 0;
diff --git a/AssetStudio/FileReader.cs b/AssetStudio/FileReader.cs
index 05fd8af..74c8e6a 100644
--- a/AssetStudio/FileReader.cs
+++ b/AssetStudio/FileReader.cs
@@ -13,7 +13,7 @@ namespace AssetStudio
         private static readonly byte[] brotliMagic = { 0x62, 0x72, 0x6F, 0x74, 0x6C, 0x69 };
         private static readonly byte[] zipMagic = { 0x50, 0x4B, 0x03, 0x04 };
         private static readonly byte[] zipSpannedMagic = { 0x50, 0x4B, 0x07, 0x08 };
-        private static readonly byte[] unityFsMagic = {0x55, 0x6E, 0x69, 0x74, 0x79, 0x46, 0x53};
+        private static readonly byte[] unityFsMagic = {0x55, 0x6E, 0x69, 0x74, 0x79, 0x46, 0x53, 0x00};
         private static readonly int headerBuffLen = 1152;
         private static byte[] headerBuff = new byte[headerBuffLen];
 
@@ -43,7 +43,6 @@ namespace AssetStudio
                     CheckBundleDataOffset(buff);
                     return FileType.BundleFile;
                 case "UnityWebData1.0":
-                    return FileType.WebFile;
                 case "TuanjieWebData1.0":
                     return FileType.WebFile;
                 default:
@@ -83,7 +82,7 @@ namespace AssetStudio
             }
         }
 
-        private bool IsSerializedFile(Span<byte> buff)
+        private bool IsSerializedFile(ReadOnlySpan<byte> buff)
         {
             var fileSize = BaseStream.Length;
             if (fileSize < 20)
@@ -129,12 +128,10 @@ namespace AssetStudio
                 return true;
             }
 
-            Position = firstOffset;
-            _ = this.ReadStringToNull();
-            _ = this.ReadUInt32();
-            _ = this.ReadStringToNull();
-            _ = this.ReadStringToNull();
-            var bundleSize = this.ReadInt64();
+            var pos = firstOffset + 12;
+            pos += buff.Slice(pos).ReadStringToNull().Length + 1;
+            pos += buff.Slice(pos).ReadStringToNull().Length + 1;
+            var bundleSize = buff.ReadInt64(pos, Endian == EndianType.BigEndian);
             if (bundleSize > 200 && firstOffset + bundleSize < lastOffset)
             {
                 Position = firstOffset;