diff --git a/src/Renci.SshNet/Sftp/SftpFileStream.cs b/src/Renci.SshNet/Sftp/SftpFileStream.cs
index ecb424567..7e91e8a5c 100644
--- a/src/Renci.SshNet/Sftp/SftpFileStream.cs
+++ b/src/Renci.SshNet/Sftp/SftpFileStream.cs
@@ -6,6 +6,7 @@
 #if FEATURE_TAP
 using System.Threading.Tasks;
 #endif
+using System.Reflection;
 
 namespace Renci.SshNet.Sftp
 {
@@ -283,8 +284,8 @@ internal SftpFileStream(ISftpSession session, string path, FileMode mode, FileAc
             // that ensures we always receive or send the max. number of bytes in a single SSH_FXP_READ
             // or SSH_FXP_WRITE message
 
-            _readBufferSize = (int) session.CalculateOptimalReadLength((uint) bufferSize);
-            _writeBufferSize = (int) session.CalculateOptimalWriteLength((uint) bufferSize, _handle);
+            _readBufferSize = (int)session.CalculateOptimalReadLength((uint)bufferSize);
+            _writeBufferSize = (int)session.CalculateOptimalWriteLength((uint)bufferSize, _handle);
 
             if (mode == FileMode.Append)
             {
@@ -381,7 +382,7 @@ internal static async Task<SftpFileStream> OpenAsync(ISftpSession session, strin
                         await session.RequestCloseAsync(handle, cancellationToken).ConfigureAwait(false);
                     }
                     catch
-                    { 
+                    {
                         // The original exception is presumably more informative, so we just ignore this one.
                     }
                     throw;
@@ -509,7 +510,7 @@ public override int Read(byte[] buffer, int offset, int count)
                     var bytesAvailableInBuffer = _bufferLen - _bufferPosition;
                     if (bytesAvailableInBuffer <= 0)
                     {
-                        var data = _session.RequestRead(_handle, (ulong) _position, (uint) _readBufferSize);
+                        var data = _session.RequestRead(_handle, (ulong)_position, (uint)_readBufferSize);
 
                         if (data.Length == 0)
                         {
@@ -726,7 +727,7 @@ public override int ReadByte()
                 // Read more data into the internal buffer if necessary.
                 if (_bufferPosition >= _bufferLen)
                 {
-                    var data = _session.RequestRead(_handle, (ulong) _position, (uint) _readBufferSize);
+                    var data = _session.RequestRead(_handle, (ulong)_position, (uint)_readBufferSize);
                     if (data.Length == 0)
                     {
                         // We've reached EOF.
@@ -783,6 +784,8 @@ public override long Seek(long offset, SeekOrigin origin)
                     return _position;
                 }
 
+                var attributes = (SftpFileAttributes)null;
+
                 // The behaviour depends upon the read/write mode.
                 if (_bufferOwnedByWrite)
                 {
@@ -798,15 +801,16 @@ public override long Seek(long offset, SeekOrigin origin)
                             newPosn = _position + offset;
                             break;
                         case SeekOrigin.End:
-                            var attributes = _session.RequestFStat(_handle, false);
-                            newPosn = attributes.Size - offset;
+                            attributes = _session.RequestFStat(_handle, false);
+                            newPosn = attributes.Size + offset;
                             break;
                     }
 
-                    if (newPosn == -1)
+                    if (newPosn == -1 || (attributes != null && newPosn > attributes.Size))
                     {
                         throw new EndOfStreamException("End of stream.");
                     }
+
                     _position = newPosn;
                 }
                 else
@@ -829,7 +833,7 @@ public override long Seek(long offset, SeekOrigin origin)
                         if (newPosn >= (_position - _bufferPosition) &&
                            newPosn < (_position - _bufferPosition + _bufferLen))
                         {
-                            _bufferPosition = (int) (newPosn - (_position - _bufferPosition));
+                            _bufferPosition = (int)(newPosn - (_position - _bufferPosition));
                             _position = newPosn;
                             return _position;
                         }
@@ -849,12 +853,16 @@ public override long Seek(long offset, SeekOrigin origin)
                             newPosn = _position + offset;
                             break;
                         case SeekOrigin.End:
-                            var attributes = _session.RequestFStat(_handle, false);
-                            newPosn = attributes.Size - offset;
+                            if (attributes == null)
+                            {
+                                attributes = _session.RequestFStat(_handle, false);
+                            }
+
+                            newPosn = attributes.Size + offset;
                             break;
                     }
 
-                    if (newPosn < 0)
+                    if (newPosn < 0 || (attributes != null && newPosn > attributes.Size))
                     {
                         throw new EndOfStreamException();
                     }
@@ -974,7 +982,7 @@ public override void Write(byte[] buffer, int offset, int count)
                     {
                         using (var wait = new AutoResetEvent(false))
                         {
-                            _session.RequestWrite(_handle, (ulong) _position, buffer, offset, tempLen, wait);
+                            _session.RequestWrite(_handle, (ulong)_position, buffer, offset, tempLen, wait);
                         }
                     }
                     else
@@ -996,7 +1004,7 @@ public override void Write(byte[] buffer, int offset, int count)
                 {
                     using (var wait = new AutoResetEvent(false))
                     {
-                        _session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), GetOrCreateWriteBuffer(), 0, _bufferPosition, wait);
+                        _session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), GetOrCreateWriteBuffer(), 0, _bufferPosition, wait);
                     }
 
                     _bufferPosition = 0;
@@ -1106,7 +1114,7 @@ public override void WriteByte(byte value)
                 {
                     using (var wait = new AutoResetEvent(false))
                     {
-                        _session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), writeBuffer, 0, _bufferPosition, wait);
+                        _session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), writeBuffer, 0, _bufferPosition, wait);
                     }
 
                     _bufferPosition = 0;
@@ -1192,7 +1200,7 @@ private void FlushWriteBuffer()
             {
                 using (var wait = new AutoResetEvent(false))
                 {
-                    _session.RequestWrite(_handle, (ulong) (_position - _bufferPosition), _writeBuffer, 0, _bufferPosition, wait);
+                    _session.RequestWrite(_handle, (ulong)(_position - _bufferPosition), _writeBuffer, 0, _bufferPosition, wait);
                 }
 
                 _bufferPosition = 0;