diff --git a/src/StreamExtended/Network/CopyStream.cs b/src/StreamExtended/Network/CopyStream.cs
index 33a3291..197f887 100644
--- a/src/StreamExtended/Network/CopyStream.cs
+++ b/src/StreamExtended/Network/CopyStream.cs
@@ -54,6 +54,11 @@ public byte PeekByteFromBuffer(int index)
             return reader.PeekByteAsync(index, cancellationToken);
         }
 
+        public Task<byte[]> PeekBytesAsync(int index, int size, CancellationToken cancellationToken = default(CancellationToken))
+        {
+            return reader.PeekBytesAsync(index, size, cancellationToken);
+        }
+
         public void Flush()
         {
             //send out the current data from from the buffer
diff --git a/src/StreamExtended/Network/CustomBufferedPeekStream.cs b/src/StreamExtended/Network/CustomBufferedPeekStream.cs
index 01f4cb7..ab3d862 100644
--- a/src/StreamExtended/Network/CustomBufferedPeekStream.cs
+++ b/src/StreamExtended/Network/CustomBufferedPeekStream.cs
@@ -85,6 +85,17 @@ byte ICustomStreamReader.PeekByteFromBuffer(int index)
             return baseStream.PeekByteFromBuffer(index);
         }
 
+        /// <summary>
+        /// Peeks bytes asynchronous.
+        /// </summary>
+        /// <param name="index">The index.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns></returns>
+        Task<byte[]> ICustomStreamReader.PeekBytesAsync(int index, int size, CancellationToken cancellationToken)
+        {
+            return baseStream.PeekBytesAsync(index, size, cancellationToken);
+        }
+
         /// <summary>
         /// Peeks a byte asynchronous.
         /// </summary>
diff --git a/src/StreamExtended/Network/CustomBufferedStream.cs b/src/StreamExtended/Network/CustomBufferedStream.cs
index c81659c..9db04b9 100644
--- a/src/StreamExtended/Network/CustomBufferedStream.cs
+++ b/src/StreamExtended/Network/CustomBufferedStream.cs
@@ -240,6 +240,30 @@ public override int ReadByte()
             return streamBuffer[bufferPos + index];
         }
 
+        /// <summary>
+        /// Peeks bytes asynchronous.
+        /// </summary>
+        /// <param name="index">The index.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns></returns>
+        public async Task<byte[]> PeekBytesAsync(int index, int size, CancellationToken cancellationToken = default(CancellationToken))
+        {
+
+            if (Available <= index)
+            {
+                await FillBufferAsync(cancellationToken);
+            }
+
+            if (Available <= (index + size))
+            {
+                return null;
+            }
+
+            var vRet = new byte[size];
+            Array.Copy(streamBuffer, index, vRet, 0, size);
+            return vRet;
+        }
+
         /// <summary>
         /// Peeks a byte from buffer.
         /// </summary>
@@ -432,6 +456,7 @@ public bool FillBuffer()
                 else
                 {
                     closed = true;
+                    throw new IOException($"{nameof(CustomBufferedStream)} closed");
                 }
 
                 return result;
@@ -439,7 +464,7 @@ public bool FillBuffer()
             catch
             {
                 closed = true;
-                return false;
+                throw;//rethrow
             }
         }
 
@@ -481,6 +506,7 @@ public bool FillBuffer()
                 else
                 {
                     closed = true;
+                    throw new IOException($"{nameof(CustomBufferedStream)} closed");
                 }
 
                 return result;
@@ -488,7 +514,7 @@ public bool FillBuffer()
             catch
             {
                 closed = true;
-                return false;
+                throw;//rethrow
             }
         }
 
diff --git a/src/StreamExtended/Network/ICustomStreamReader.cs b/src/StreamExtended/Network/ICustomStreamReader.cs
index 058dc01..89d3278 100644
--- a/src/StreamExtended/Network/ICustomStreamReader.cs
+++ b/src/StreamExtended/Network/ICustomStreamReader.cs
@@ -37,6 +37,14 @@ public interface ICustomStreamReader
         /// <returns></returns>
         Task<int> PeekByteAsync(int index, CancellationToken cancellationToken = default(CancellationToken));
 
+        /// <summary>
+        /// Peeks bytes asynchronous.
+        /// </summary>
+        /// <param name="index">The index.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns></returns>
+        Task<byte[]> PeekBytesAsync(int index, int size, CancellationToken cancellationToken = default(CancellationToken));
+
         byte ReadByteFromBuffer();
 
         /// <summary>