diff --git a/src/Kafa/Reader/KafaReadState.cs b/src/Kafa/Reader/KafaReadState.cs
index 4518bde..37f0a91 100644
--- a/src/Kafa/Reader/KafaReadState.cs
+++ b/src/Kafa/Reader/KafaReadState.cs
@@ -6,7 +6,7 @@
 
 namespace nyingi.Kafa.Reader
 {
-    public struct KafaReadState : IDisposable
+    public sealed class KafaReadState : IDisposable
     {
         public char[] Buffer { get; private set; }
         public int[] ColMarker { get; private set; }
diff --git a/src/Kafa/Reader/KafaReader.Col.cs b/src/Kafa/Reader/KafaReader.Col.cs
index 98f4373..aa35138 100644
--- a/src/Kafa/Reader/KafaReader.Col.cs
+++ b/src/Kafa/Reader/KafaReader.Col.cs
@@ -2,7 +2,7 @@
 
 namespace nyingi.Kafa.Reader
 {
-    public partial struct KafaReader
+    public partial class KafaReader
     {
         public readonly ref struct Col
         {
@@ -20,7 +20,7 @@ public int Length
             public Col(ColEnumerable colEnumerable, int index)
             {
                 _colEnumerable = colEnumerable;
-                Value = _colEnumerable.ReadColSpan(index);
+                Value = _colEnumerable.ReadColAsSpan(index);
 
             }
 
@@ -28,7 +28,7 @@ public Col(ColEnumerable colEnumerable, string columnName)
             {
                 _colEnumerable = colEnumerable;
                 int index = _colEnumerable.ReadColByHeader(columnName);
-                Value = _colEnumerable.ReadColSpan(index);
+                Value = _colEnumerable.ReadColAsSpan(index);
             }
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -45,15 +45,15 @@ public override string ToString()
 
         }
 
-        public ref struct ColEnumerable
+        public struct ColEnumerable
         {
             private readonly KafaReader _reader;
-            private ReadOnlySpan<int> _colMarkerIndexes;
+            private ReadOnlyMemory<int> _colMarkerIndexes;
 
             public ColEnumerable(KafaReader reader, int startColIndex, int length)
             {
                 _reader = reader;
-                _colMarkerIndexes = reader.ReadColMarkerSpan(startColIndex, length);
+                _colMarkerIndexes = reader.ReadColMarkerAsMemory(startColIndex, length);
             }
 
             public int Length => _colMarkerIndexes.Length;
@@ -76,7 +76,7 @@ public int ReadColByHeader(string columnName)
             }
 
             [MethodImpl(MethodImplOptions.AggressiveInlining)]
-            public ReadOnlySpan<char> ReadColSpan(int index)
+            public ReadOnlySpan<char> ReadColAsSpan(int index)
             {
                 int lastColMarker = index + 1;
 
@@ -84,13 +84,15 @@ public ReadOnlySpan<char> ReadColSpan(int index)
                 {
                     throw new KafaException($"{index}: {nameof(index)} out of range", new ArgumentOutOfRangeException(nameof(index)));
                 }
-                int startIndex = _colMarkerIndexes[index]; 
+                int startIndex = _colMarkerIndexes.Span[index]; 
                 startIndex = startIndex == 0 ? 0 : startIndex + 1; // SKIP Separator
-                int lastIndex = _colMarkerIndexes[lastColMarker];
+                int lastIndex = _colMarkerIndexes.Span[lastColMarker];
                 // TODO: Simplify this checks
                 lastIndex = _reader.HasCRLF && lastColMarker == _colMarkerIndexes.Length - 1 && lastIndex != _reader.LastBufferIndex 
                                 ? lastIndex - 1 : lastIndex;
-                return _reader.ReadColSpan(startIndex, lastIndex);
+
+                var mem = _reader.ReadColAsMemory(startIndex, lastIndex);
+                return mem.Span;
             } 
 
 
@@ -107,7 +109,7 @@ public readonly bool TryParse<T>(ReadOnlySpan<char> colValue, out T? result) whe
             public Enumerator GetEnumerator() => new Enumerator(this);
 
 
-            public ref struct Enumerator
+            public struct Enumerator
             {
                 private int _index = -1;
 
diff --git a/src/Kafa/Reader/KafaReader.Row.cs b/src/Kafa/Reader/KafaReader.Row.cs
index 747cff6..5a7bb06 100644
--- a/src/Kafa/Reader/KafaReader.Row.cs
+++ b/src/Kafa/Reader/KafaReader.Row.cs
@@ -4,7 +4,7 @@
 
 namespace nyingi.Kafa.Reader
 {
-    public partial struct KafaReader
+    public partial class KafaReader
     {
 
         public readonly struct Row
diff --git a/src/Kafa/Reader/KafaReader.cs b/src/Kafa/Reader/KafaReader.cs
index 465e715..1a67817 100644
--- a/src/Kafa/Reader/KafaReader.cs
+++ b/src/Kafa/Reader/KafaReader.cs
@@ -5,11 +5,11 @@
 
 namespace nyingi.Kafa.Reader
 {
-    public partial struct KafaReader : IDisposable
+    public partial class KafaReader : IDisposable
     {
         private readonly KafaReadState _kafaReadState;
         private readonly CultureInfo? cultureInfo;
-        public KafaReader(in KafaReadState kafaReadState)
+        public KafaReader(KafaReadState kafaReadState)
         {
             _kafaReadState = kafaReadState;
             cultureInfo = kafaReadState.Options.CultureInfo;
@@ -31,7 +31,7 @@ public KafaReader(in KafaReadState kafaReadState)
         public OrderedDictionary? Headers => _kafaReadState.Headers;
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public readonly ReadOnlyMemory<char> ReadRowSpan(int index, out int lastColMarkerIndex)
+        public ReadOnlyMemory<char> ReadRowSpan(int index, out int lastColMarkerIndex)
         {
             lastColMarkerIndex = index + ColumnCount;
 
@@ -51,9 +51,9 @@ public readonly ReadOnlyMemory<char> ReadRowSpan(int index, out int lastColMarke
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public readonly ReadOnlySpan<char> ReadColSpan(int startIndex, int lastIndex)
+        public ReadOnlyMemory<char> ReadColAsMemory(int startIndex, int lastIndex)
         {
-            return _kafaReadState.Buffer.AsSpan(startIndex, lastIndex - startIndex);
+            return _kafaReadState.Buffer.AsMemory(startIndex, lastIndex - startIndex);
         }
 
         public RowEnumerable GetRows(Range range)
@@ -67,14 +67,14 @@ public RowEnumerable GetRows()
             return new(this);
         }
 
-        private ReadOnlySpan<int> ReadColMarkerSpan(int index, int length)
+        private ReadOnlyMemory<int> ReadColMarkerAsMemory(int index, int length)
         {
             if(index < 0 || index + length > _kafaReadState.ColMarkerLength)
             {
                 throw new KafaException($"{index}: {nameof(index)} out of range", new ArgumentOutOfRangeException(nameof(index)));
             }
 
-            return _kafaReadState.ColMarker.AsSpan(index, length);
+            return _kafaReadState.ColMarker.AsMemory(index, length);
         }
 
         public void Dispose()
diff --git a/src/Kafa/Writer/KafaPooledWriter.cs b/src/Kafa/Writer/KafaPooledWriter.cs
index 950545b..8bef05d 100644
--- a/src/Kafa/Writer/KafaPooledWriter.cs
+++ b/src/Kafa/Writer/KafaPooledWriter.cs
@@ -2,7 +2,7 @@
 
 namespace nyingi.Kafa.Writer
 {
-    public sealed class KafaPooledWriter : IBufferWriter<byte>, IDisposable
+    public class KafaPooledWriter : IBufferWriter<byte>, IDisposable
     {
         private const int DefaultBufferLength = 65556;
         private byte[] _buffer;
diff --git a/src/Kafa/Writer/KafaWriter.cs b/src/Kafa/Writer/KafaWriter.cs
index 4d3348d..cc731db 100644
--- a/src/Kafa/Writer/KafaWriter.cs
+++ b/src/Kafa/Writer/KafaWriter.cs
@@ -54,7 +54,7 @@ public void Write(ReadOnlySpan<byte> values)
             }
             else
             {
-                _kafaPooledWriter?.Write(values);
+                _kafaPooledWriter.Write(values);
             }
         }
 
@@ -62,7 +62,7 @@ public void Flush()
         {
             if (_stream != null)
             {
-                _stream.Write(_kafaPooledWriter!.WrittenAsSpan);
+                _stream.Write(_kafaPooledWriter.WrittenAsSpan);
                 _stream.Flush();
             }
         }