diff --git a/Sources/NIOExtras/DebugInboundEventsHandler.swift b/Sources/NIOExtras/DebugInboundEventsHandler.swift
index 10c2e5b9..5e25693c 100644
--- a/Sources/NIOExtras/DebugInboundEventsHandler.swift
+++ b/Sources/NIOExtras/DebugInboundEventsHandler.swift
@@ -174,3 +174,8 @@ public class DebugInboundEventsHandler: ChannelInboundHandler {
         fflush(stdout)
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension DebugInboundEventsHandler: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/DebugOutboundEventsHandler.swift b/Sources/NIOExtras/DebugOutboundEventsHandler.swift
index eb0437a7..6cff4581 100644
--- a/Sources/NIOExtras/DebugOutboundEventsHandler.swift
+++ b/Sources/NIOExtras/DebugOutboundEventsHandler.swift
@@ -170,3 +170,8 @@ public class DebugOutboundEventsHandler: ChannelOutboundHandler {
         fflush(stdout)
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension DebugOutboundEventsHandler: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/FixedLengthFrameDecoder.swift b/Sources/NIOExtras/FixedLengthFrameDecoder.swift
index 4f4a3260..326dc77b 100644
--- a/Sources/NIOExtras/FixedLengthFrameDecoder.swift
+++ b/Sources/NIOExtras/FixedLengthFrameDecoder.swift
@@ -76,3 +76,8 @@ public final class FixedLengthFrameDecoder: ByteToMessageDecoder {
         return .needMoreData
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension FixedLengthFrameDecoder: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/JSONRPCFraming+ContentLengthHeader.swift b/Sources/NIOExtras/JSONRPCFraming+ContentLengthHeader.swift
index 099e93cd..9bf462d0 100644
--- a/Sources/NIOExtras/JSONRPCFraming+ContentLengthHeader.swift
+++ b/Sources/NIOExtras/JSONRPCFraming+ContentLengthHeader.swift
@@ -214,3 +214,13 @@ extension String {
         return self[firstElementIndex ..< lastElementIndex.base]
     }
 }
+
+
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension NIOJSONRPCFraming.ContentLengthHeaderFrameDecoder: Sendable {}
+
+@available(*, unavailable)
+extension NIOJSONRPCFraming.ContentLengthHeaderFrameEncoder: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/LengthFieldBasedFrameDecoder.swift b/Sources/NIOExtras/LengthFieldBasedFrameDecoder.swift
index 071591a5..6875e862 100644
--- a/Sources/NIOExtras/LengthFieldBasedFrameDecoder.swift
+++ b/Sources/NIOExtras/LengthFieldBasedFrameDecoder.swift
@@ -246,3 +246,8 @@ public final class LengthFieldBasedFrameDecoder: ByteToMessageDecoder {
         return frameLength
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension LengthFieldBasedFrameDecoder: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/LengthFieldPrepender.swift b/Sources/NIOExtras/LengthFieldPrepender.swift
index 37d797ca..fdabf79f 100644
--- a/Sources/NIOExtras/LengthFieldPrepender.swift
+++ b/Sources/NIOExtras/LengthFieldPrepender.swift
@@ -144,3 +144,8 @@ public final class LengthFieldPrepender: ChannelOutboundHandler {
         context.write(data, promise: promise)
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension LengthFieldPrepender: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/LineBasedFrameDecoder.swift b/Sources/NIOExtras/LineBasedFrameDecoder.swift
index fd7a809c..cc1b53b2 100644
--- a/Sources/NIOExtras/LineBasedFrameDecoder.swift
+++ b/Sources/NIOExtras/LineBasedFrameDecoder.swift
@@ -91,3 +91,8 @@ public class LineBasedFrameDecoder: ByteToMessageDecoder {
         return nil
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension LineBasedFrameDecoder: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/NIOLengthFieldBitLength.swift b/Sources/NIOExtras/NIOLengthFieldBitLength.swift
index a41ab117..8bbff5b7 100644
--- a/Sources/NIOExtras/NIOLengthFieldBitLength.swift
+++ b/Sources/NIOExtras/NIOLengthFieldBitLength.swift
@@ -12,8 +12,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+import NIOCore
+
 /// A struct to describe the length of a piece of data in bits
-public struct NIOLengthFieldBitLength {
+public struct NIOLengthFieldBitLength: NIOSendable {
     internal enum Backing {
         case bits8
         case bits16
diff --git a/Sources/NIOExtras/PCAPRingBuffer.swift b/Sources/NIOExtras/PCAPRingBuffer.swift
index 4273d28e..93648108 100644
--- a/Sources/NIOExtras/PCAPRingBuffer.swift
+++ b/Sources/NIOExtras/PCAPRingBuffer.swift
@@ -96,3 +96,8 @@ public class NIOPCAPRingBuffer {
         return toReturn
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension NIOPCAPRingBuffer: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/RequestResponseHandler.swift b/Sources/NIOExtras/RequestResponseHandler.swift
index 907ce2ec..1c91e1eb 100644
--- a/Sources/NIOExtras/RequestResponseHandler.swift
+++ b/Sources/NIOExtras/RequestResponseHandler.swift
@@ -119,3 +119,8 @@ public final class RequestResponseHandler<Request, Response>: ChannelDuplexHandl
         }
     }
 }
+
+#if swift(>=5.6)
+@available(*, unavailable)
+extension RequestResponseHandler: Sendable {}
+#endif
diff --git a/Sources/NIOExtras/WritePCAPHandler.swift b/Sources/NIOExtras/WritePCAPHandler.swift
index 92bcf4ec..70b6d8eb 100644
--- a/Sources/NIOExtras/WritePCAPHandler.swift
+++ b/Sources/NIOExtras/WritePCAPHandler.swift
@@ -290,6 +290,11 @@ public class NIOWritePCAPHandler: RemovableChannelHandler {
     }
 }
 
+#if swift(>=5.6)
+@available(*, unavailable)
+extension NIOWritePCAPHandler: Sendable {}
+#endif
+
 extension NIOWritePCAPHandler: ChannelDuplexHandler {
     public typealias InboundIn = ByteBuffer
     public typealias InboundOut = ByteBuffer