diff --git a/Obvs.Serialization.MessagePack/Configuration/FluentConfigExtensions.cs b/Obvs.Serialization.MessagePack/Configuration/FluentConfigExtensions.cs
index 4f2aeb8f..5e0d06cb 100644
--- a/Obvs.Serialization.MessagePack/Configuration/FluentConfigExtensions.cs
+++ b/Obvs.Serialization.MessagePack/Configuration/FluentConfigExtensions.cs
@@ -1,9 +1,11 @@
-using Obvs.Configuration;
+using System;
+using Obvs.Configuration;
 
 namespace Obvs.Serialization.MessagePack.Configuration
 {
     public static class FluentConfigExtensions
     {
+        [Obsolete("MsgPack.Cli is no longer maintained; use SerializedAsMessagePackCSharp() from Obvs.Serialization.MessagePack-CSharp instead")]
         public static ICanCreateEndpointAsClientOrServer<TMessage, TCommand, TEvent, TRequest, TResponse> SerializedAsMsgPack<TMessage, TCommand, TEvent, TRequest, TResponse>(this ICanSpecifyEndpointSerializers<TMessage, TCommand, TEvent, TRequest, TResponse> config)
             where TMessage : class
             where TCommand : class, TMessage
diff --git a/Obvs.Serialization.MessagePack/MsgPackMessageDeserializer.cs b/Obvs.Serialization.MessagePack/MsgPackMessageDeserializer.cs
index 0c27685b..12bd8c9e 100644
--- a/Obvs.Serialization.MessagePack/MsgPackMessageDeserializer.cs
+++ b/Obvs.Serialization.MessagePack/MsgPackMessageDeserializer.cs
@@ -1,8 +1,10 @@
+using System;
 using System.IO;
 using MsgPack.Serialization;
 
 namespace Obvs.Serialization.MessagePack
 {
+    [Obsolete("MsgPack.Cli is no longer maintained; use Obvs.Serialization.MessagePack-CSharp instead")]
     public class MsgPackMessageDeserializer<TMessage> : MessageDeserializerBase<TMessage> 
         where TMessage : class
     {
diff --git a/Obvs.Serialization.MessagePack/MsgPackMessageDeserializerFactory.cs b/Obvs.Serialization.MessagePack/MsgPackMessageDeserializerFactory.cs
index 0d9fe041..f25cde94 100644
--- a/Obvs.Serialization.MessagePack/MsgPackMessageDeserializerFactory.cs
+++ b/Obvs.Serialization.MessagePack/MsgPackMessageDeserializerFactory.cs
@@ -6,6 +6,7 @@
 
 namespace Obvs.Serialization.MessagePack
 {
+    [Obsolete("MsgPack.Cli is no longer maintained; use Obvs.Serialization.MessagePack-CSharp instead")]
     public class MsgPackMessageDeserializerFactory : IMessageDeserializerFactory
     {
         public IEnumerable<IMessageDeserializer<TMessage>> Create<TMessage, TServiceMessage>(Func<Assembly, bool> assemblyFilter = null, Func<Type, bool> typeFilter = null)
diff --git a/Obvs.Serialization.MessagePack/MsgPackMessageSerializer.cs b/Obvs.Serialization.MessagePack/MsgPackMessageSerializer.cs
index 04c6cbdb..d678bd6d 100644
--- a/Obvs.Serialization.MessagePack/MsgPackMessageSerializer.cs
+++ b/Obvs.Serialization.MessagePack/MsgPackMessageSerializer.cs
@@ -1,8 +1,10 @@
-using System.IO;
+using System;
+using System.IO;
 using MsgPack.Serialization;
 
 namespace Obvs.Serialization.MessagePack
 {
+    [Obsolete("MsgPack.Cli is no longer maintained; use Obvs.Serialization.MessagePack-CSharp instead")]
     public class MsgPackMessageSerializer : IMessageSerializer
     {
         public void Serialize(Stream destination, object message)
diff --git a/Obvs.Serialization.MessagePack/Obvs.Serialization.MessagePack.csproj b/Obvs.Serialization.MessagePack/Obvs.Serialization.MessagePack.csproj
index 8d147a57..96631365 100644
--- a/Obvs.Serialization.MessagePack/Obvs.Serialization.MessagePack.csproj
+++ b/Obvs.Serialization.MessagePack/Obvs.Serialization.MessagePack.csproj
@@ -7,8 +7,8 @@
     <Version>1.0.0</Version>
     <Authors />
     <PackageProjectUrl>http://christopherread.github.io/Obvs</PackageProjectUrl>
-    <PackageReleaseNotes>Minor dependency update</PackageReleaseNotes>
-    <Description>MessagePack serialization for Obvs</Description>
+    <PackageReleaseNotes>Deprecated: MsgPack.Cli is no longer maintained. Use Obvs.Serialization.MessagePack-CSharp instead.</PackageReleaseNotes>
+    <Description>Deprecated: use Obvs.Serialization.MessagePack-CSharp. MessagePack serialization for Obvs using MsgPack.Cli, which is no longer maintained.</Description>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/Obvs.Serialization.Tests/TestMsgPackSerialization.cs b/Obvs.Serialization.Tests/TestMsgPackSerialization.cs
index 1e8cb804..77516b22 100644
--- a/Obvs.Serialization.Tests/TestMsgPackSerialization.cs
+++ b/Obvs.Serialization.Tests/TestMsgPackSerialization.cs
@@ -1,4 +1,8 @@
+// These tests exercise the deprecated MsgPack.Cli serializer on purpose
+#pragma warning disable CS0618
+
 using System;
+using System.Reflection;
 using FakeItEasy;
 using Xunit;
 using Obvs.Configuration;
@@ -11,6 +15,30 @@ namespace Obvs.Serialization.Tests
 
     public class TestMsgPackSerialization
     {
+        [Theory]
+        [InlineData(typeof(MsgPackMessageSerializer))]
+        [InlineData(typeof(MsgPackMessageDeserializer<>))]
+        [InlineData(typeof(MsgPackMessageDeserializerFactory))]
+        public void ShouldBeObsoleteInFavourOfMessagePackCSharp(Type type)
+        {
+            var obsolete = type.GetCustomAttribute<ObsoleteAttribute>();
+
+            Assert.NotNull(obsolete);
+            Assert.False(obsolete.IsError);
+            Assert.Contains("Obvs.Serialization.MessagePack-CSharp", obsolete.Message);
+        }
+
+        [Fact]
+        public void FluentConfigShouldBeObsoleteInFavourOfMessagePackCSharp()
+        {
+            // Obvs.Serialization.MessagePack-CSharp has a class with the same full name, so look it up in this package's assembly
+            var extensions = typeof(MsgPackMessageSerializer).Assembly.GetType("Obvs.Serialization.MessagePack.Configuration.FluentConfigExtensions");
+            var obsolete = extensions.GetMethod("SerializedAsMsgPack").GetCustomAttribute<ObsoleteAttribute>();
+
+            Assert.NotNull(obsolete);
+            Assert.Contains("SerializedAsMessagePackCSharp", obsolete.Message);
+        }
+
         [Fact]
         public void ShouldSerializeToMsgPack()
         {
diff --git a/README.md b/README.md
index 7b37ded7..01410af4 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@
 ### Extensions
 
 * Transports: ActiveMQ / RabbitMQ / NetMQ / AzureServiceBus / Kafka / EventStore
-* Serialization: XML / JSON.Net / NetJson / ProtoBuf / MsgPack
+* Serialization: XML / JSON.Net / NetJson / ProtoBuf / MessagePack (via MessagePack-CSharp; the MsgPack.Cli-based package is deprecated)
 * Logging: NLog / log4net
 * Monitoring: Performance Counters / ElasticSearch