diff --git a/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisHubLifetimeManagerBenchmark.cs b/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisHubLifetimeManagerBenchmark.cs
index 40426e995d..cb21cce57d 100644
--- a/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisHubLifetimeManagerBenchmark.cs
+++ b/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisHubLifetimeManagerBenchmark.cs
@@ -22,10 +22,10 @@ namespace Microsoft.AspNetCore.SignalR.Microbenchmarks
         private RedisHubLifetimeManager<TestHub> _manager2;
         private TestClient[] _clients;
         private object[] _args;
-        private List<string> _excludedIds = new List<string>();
-        private List<string> _sendIds = new List<string>();
-        private List<string> _groups = new List<string>();
-        private List<string> _users = new List<string>();
+        private readonly List<string> _excludedIds = new List<string>();
+        private readonly List<string> _sendIds = new List<string>();
+        private readonly List<string> _groups = new List<string>();
+        private readonly List<string> _users = new List<string>();
 
         private const int ClientCount = 20;
 
diff --git a/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisProtocolBenchmark.cs b/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisProtocolBenchmark.cs
index c856613edb..5eec1d66bf 100644
--- a/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisProtocolBenchmark.cs
+++ b/benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/RedisProtocolBenchmark.cs
@@ -119,7 +119,7 @@ namespace Microsoft.AspNetCore.SignalR.Microbenchmarks
 
         private class DummyProtocol: IHubProtocol
         {
-            private static byte[] _fixedOutput = new byte[] { 0x68, 0x68, 0x6C, 0x6C, 0x6F };
+            private static readonly byte[] _fixedOutput = new byte[] { 0x68, 0x68, 0x6C, 0x6C, 0x6F };
 
             public string Name { get; }
 
diff --git a/samples/ClientSample/Tcp/TcpConnection.cs b/samples/ClientSample/Tcp/TcpConnection.cs
index fffeef17e6..d2656c1f80 100644
--- a/samples/ClientSample/Tcp/TcpConnection.cs
+++ b/samples/ClientSample/Tcp/TcpConnection.cs
@@ -16,8 +16,8 @@ namespace ClientSample
         private volatile bool _aborted;
         private readonly EndPoint _endPoint;
         private IDuplexPipe _application;
-        private SocketSender _sender;
-        private SocketReceiver _receiver;
+        private readonly SocketSender _sender;
+        private readonly SocketReceiver _receiver;
 
         public TcpConnection(EndPoint endPoint)
         {
diff --git a/samples/SocialWeather/FormatterResolver.cs b/samples/SocialWeather/FormatterResolver.cs
index 08cc1f6860..2a8912aa8f 100644
--- a/samples/SocialWeather/FormatterResolver.cs
+++ b/samples/SocialWeather/FormatterResolver.cs
@@ -9,9 +9,9 @@ namespace SocialWeather
 {
     public class FormatterResolver
     {
-        private IServiceProvider _serviceProvider;
+        private readonly IServiceProvider _serviceProvider;
 
-        private Dictionary<string, Dictionary<Type, Type>> _formatters
+        private readonly Dictionary<string, Dictionary<Type, Type>> _formatters
             = new Dictionary<string, Dictionary<Type, Type>>();
 
         public FormatterResolver(IServiceProvider serviceProvider)
diff --git a/samples/SocialWeather/Json/JSonStreamFormatter.cs b/samples/SocialWeather/Json/JSonStreamFormatter.cs
index dbd590eca7..c1e8f8f5d6 100644
--- a/samples/SocialWeather/Json/JSonStreamFormatter.cs
+++ b/samples/SocialWeather/Json/JSonStreamFormatter.cs
@@ -9,7 +9,7 @@ namespace SocialWeather.Json
 {
     public class JsonStreamFormatter<T> : IStreamFormatter<T>
     {
-        private JsonSerializer _serializer = new JsonSerializer();
+        private readonly JsonSerializer _serializer = new JsonSerializer();
 
         public async Task<T> ReadAsync(Stream stream)
         {
diff --git a/src/Microsoft.AspNetCore.Http.Connections.Client/Internal/ServerSentEventsMessageParser.cs b/src/Microsoft.AspNetCore.Http.Connections.Client/Internal/ServerSentEventsMessageParser.cs
index 64fbba5914..ebc603c7d4 100644
--- a/src/Microsoft.AspNetCore.Http.Connections.Client/Internal/ServerSentEventsMessageParser.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections.Client/Internal/ServerSentEventsMessageParser.cs
@@ -15,12 +15,12 @@ namespace Microsoft.AspNetCore.Http.Connections.Client.Internal
         private const byte ByteLF = (byte)'\n';
         private const byte ByteColon = (byte)':';
 
-        private static byte[] _dataPrefix = Encoding.UTF8.GetBytes("data: ");
-        private static byte[] _sseLineEnding = Encoding.UTF8.GetBytes("\r\n");
-        private static byte[] _newLine = Encoding.UTF8.GetBytes(Environment.NewLine);
+        private static readonly byte[] _dataPrefix = Encoding.UTF8.GetBytes("data: ");
+        private static readonly byte[] _sseLineEnding = Encoding.UTF8.GetBytes("\r\n");
+        private static readonly byte[] _newLine = Encoding.UTF8.GetBytes(Environment.NewLine);
 
         private InternalParseState _internalParserState = InternalParseState.ReadMessagePayload;
-        private List<byte[]> _data = new List<byte[]>();
+        private readonly List<byte[]> _data = new List<byte[]>();
 
         public ParseResult ParseMessage(ReadOnlySequence<byte> buffer, out SequencePosition consumed, out SequencePosition examined, out byte[] message)
         {
diff --git a/src/Microsoft.AspNetCore.Http.Connections/HttpConnectionManager.cs b/src/Microsoft.AspNetCore.Http.Connections/HttpConnectionManager.cs
index 2b42146ac4..de9c37256e 100644
--- a/src/Microsoft.AspNetCore.Http.Connections/HttpConnectionManager.cs
+++ b/src/Microsoft.AspNetCore.Http.Connections/HttpConnectionManager.cs
@@ -30,7 +30,7 @@ namespace Microsoft.AspNetCore.Http.Connections
         private Timer _timer;
         private readonly ILogger<HttpConnectionManager> _logger;
         private readonly ILogger<HttpConnectionContext> _connectionLogger;
-        private object _executionLock = new object();
+        private readonly object _executionLock = new object();
         private bool _disposed;
 
         public HttpConnectionManager(ILoggerFactory loggerFactory, IApplicationLifetime appLifetime)
diff --git a/src/Microsoft.AspNetCore.SignalR.Core/HubCallerClients.cs b/src/Microsoft.AspNetCore.SignalR.Core/HubCallerClients.cs
index 7c6f109732..3fafdabbab 100644
--- a/src/Microsoft.AspNetCore.SignalR.Core/HubCallerClients.cs
+++ b/src/Microsoft.AspNetCore.SignalR.Core/HubCallerClients.cs
@@ -7,9 +7,9 @@ namespace Microsoft.AspNetCore.SignalR
 {
     public class HubCallerClients : IHubCallerClients
     {
-        private string _connectionId;
-        private IHubClients _hubClients;
-        private string[] _currentConnectionId;
+        private readonly string _connectionId;
+        private readonly IHubClients _hubClients;
+        private readonly string[] _currentConnectionId;
 
         public HubCallerClients(IHubClients hubClients, string connectionId)
         {
diff --git a/src/Microsoft.AspNetCore.SignalR.Core/TypedClientBuilder.cs b/src/Microsoft.AspNetCore.SignalR.Core/TypedClientBuilder.cs
index 83bc3e45ac..99b7f6aad5 100644
--- a/src/Microsoft.AspNetCore.SignalR.Core/TypedClientBuilder.cs
+++ b/src/Microsoft.AspNetCore.SignalR.Core/TypedClientBuilder.cs
@@ -16,7 +16,7 @@ namespace Microsoft.AspNetCore.SignalR
         private const string ClientModuleName = "Microsoft.AspNetCore.SignalR.TypedClientBuilder";
 
         // There is one static instance of _builder per T
-        private static Lazy<Func<IClientProxy, T>> _builder = new Lazy<Func<IClientProxy, T>>(() => GenerateClientBuilder());
+        private static readonly Lazy<Func<IClientProxy, T>> _builder = new Lazy<Func<IClientProxy, T>>(() => GenerateClientBuilder());
 
         public static T Build(IClientProxy proxy)
         {
diff --git a/src/Microsoft.AspNetCore.SignalR.Core/TypedHubClients.cs b/src/Microsoft.AspNetCore.SignalR.Core/TypedHubClients.cs
index 0ac92057f6..d984dbd99e 100644
--- a/src/Microsoft.AspNetCore.SignalR.Core/TypedHubClients.cs
+++ b/src/Microsoft.AspNetCore.SignalR.Core/TypedHubClients.cs
@@ -7,7 +7,7 @@ namespace Microsoft.AspNetCore.SignalR
 {
     internal class TypedHubClients<T> : IHubCallerClients<T>
     {
-        private IHubCallerClients _hubClients;
+        private readonly IHubCallerClients _hubClients;
 
         public TypedHubClients(IHubCallerClients dynamicContext)
         {
diff --git a/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs b/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
index aeae6d1df2..a09deaffbb 100644
--- a/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
+++ b/src/Microsoft.AspNetCore.SignalR.Redis/RedisHubLifetimeManager.cs
@@ -579,8 +579,8 @@ namespace Microsoft.AspNetCore.SignalR.Redis
 
         private class GroupData
         {
-            public SemaphoreSlim Lock = new SemaphoreSlim(1, 1);
-            public HubConnectionStore Connections = new HubConnectionStore();
+            public readonly SemaphoreSlim Lock = new SemaphoreSlim(1, 1);
+            public readonly HubConnectionStore Connections = new HubConnectionStore();
         }
 
         private interface IRedisFeature
diff --git a/test/Microsoft.AspNetCore.Http.Connections.Tests/MapConnectionHandlerTests.cs b/test/Microsoft.AspNetCore.Http.Connections.Tests/MapConnectionHandlerTests.cs
index 57adeb80ef..0d24cf0e61 100644
--- a/test/Microsoft.AspNetCore.Http.Connections.Tests/MapConnectionHandlerTests.cs
+++ b/test/Microsoft.AspNetCore.Http.Connections.Tests/MapConnectionHandlerTests.cs
@@ -22,7 +22,7 @@ namespace Microsoft.AspNetCore.Http.Connections.Tests
 {
     public class MapConnectionHandlerTests
     {
-        private ITestOutputHelper _output;
+        private readonly ITestOutputHelper _output;
 
         public MapConnectionHandlerTests(ITestOutputHelper output)
         {
diff --git a/test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/MessagePackHubProtocolTests.cs b/test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/MessagePackHubProtocolTests.cs
index 10604984ec..e6bdb6090d 100644
--- a/test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/MessagePackHubProtocolTests.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/MessagePackHubProtocolTests.cs
@@ -27,7 +27,7 @@ namespace Microsoft.AspNetCore.SignalR.Common.Tests.Internal.Protocol
             { "ValueWithNewLines", "Also\nWorks\r\nFine" },
         };
 
-        private static MessagePackObject TestHeadersSerialized = Map(
+        private static readonly MessagePackObject TestHeadersSerialized = Map(
             ("Foo", "Bar"),
             ("KeyWith\nNew\r\nLines", "Still Works"),
             ("ValueWithNewLines", "Also\nWorks\r\nFine"));
@@ -35,7 +35,7 @@ namespace Microsoft.AspNetCore.SignalR.Common.Tests.Internal.Protocol
         private static readonly MessagePackHubProtocol _hubProtocol
             = new MessagePackHubProtocol();
 
-        private static MessagePackObject CustomObjectSerialized = Map(
+        private static readonly MessagePackObject CustomObjectSerialized = Map(
             ("ByteArrProp", new MessagePackObject(new byte[] { 1, 2, 3 }, isBinary: true)),
             ("DateTimeProp", new MessagePackObject(Timestamp.FromDateTime(new DateTime(2017, 4, 11)))),
             ("DoubleProp", 6.2831853071),
diff --git a/test/Microsoft.AspNetCore.SignalR.Redis.Tests/Docker.cs b/test/Microsoft.AspNetCore.SignalR.Redis.Tests/Docker.cs
index f48f30f3ba..fcc7ba066d 100644
--- a/test/Microsoft.AspNetCore.SignalR.Redis.Tests/Docker.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Redis.Tests/Docker.cs
@@ -16,7 +16,7 @@ namespace Microsoft.AspNetCore.SignalR.Redis.Tests
         private static readonly string _exeSuffix = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? ".exe" : string.Empty;
 
         private static readonly string _dockerContainerName = "redisTestContainer";
-        private static Lazy<Docker> _instance = new Lazy<Docker>(Create);
+        private static readonly Lazy<Docker> _instance = new Lazy<Docker>(Create);
 
         public static Docker Default => _instance.Value;
 
diff --git a/test/Microsoft.AspNetCore.SignalR.Tests.Utils/ServerFixture.cs b/test/Microsoft.AspNetCore.SignalR.Tests.Utils/ServerFixture.cs
index 805bedffaa..51aa1a1502 100644
--- a/test/Microsoft.AspNetCore.SignalR.Tests.Utils/ServerFixture.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Tests.Utils/ServerFixture.cs
@@ -148,7 +148,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
         // TestSink doesn't seem to be thread-safe :(.
         private class LogSinkProvider : ILoggerProvider
         {
-            private ConcurrentQueue<LogRecord> _logs = new ConcurrentQueue<LogRecord>();
+            private readonly ConcurrentQueue<LogRecord> _logs = new ConcurrentQueue<LogRecord>();
 
             public ILogger CreateLogger(string categoryName)
             {
@@ -179,8 +179,8 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 
             private class LogSinkLogger : ILogger
             {
-                private string _categoryName;
-                private LogSinkProvider _logSinkProvider;
+                private readonly string _categoryName;
+                private readonly LogSinkProvider _logSinkProvider;
 
                 public LogSinkLogger(string categoryName, LogSinkProvider logSinkProvider)
                 {
diff --git a/test/Microsoft.AspNetCore.SignalR.Tests.Utils/TestConnectionMultiplexer.cs b/test/Microsoft.AspNetCore.SignalR.Tests.Utils/TestConnectionMultiplexer.cs
index 412ccf0cd4..2852f9c64c 100644
--- a/test/Microsoft.AspNetCore.SignalR.Tests.Utils/TestConnectionMultiplexer.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Tests.Utils/TestConnectionMultiplexer.cs
@@ -70,7 +70,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             remove { }
         }
 
-        private ISubscriber _subscriber;
+        private readonly ISubscriber _subscriber;
 
         public TestConnectionMultiplexer(TestRedisServer server)
         {
@@ -210,7 +210,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 
     public class TestRedisServer
     {
-        private ConcurrentDictionary<RedisChannel, List<Action<RedisChannel, RedisValue>>> _subscriptions =
+        private readonly ConcurrentDictionary<RedisChannel, List<Action<RedisChannel, RedisValue>>> _subscriptions =
             new ConcurrentDictionary<RedisChannel, List<Action<RedisChannel, RedisValue>>>();
 
         public long Publish(RedisChannel channel, RedisValue message, CommandFlags flags = CommandFlags.None)
diff --git a/test/Microsoft.AspNetCore.SignalR.Tests/CancellationDisposable.cs b/test/Microsoft.AspNetCore.SignalR.Tests/CancellationDisposable.cs
index 50a02883ca..1400026549 100644
--- a/test/Microsoft.AspNetCore.SignalR.Tests/CancellationDisposable.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Tests/CancellationDisposable.cs
@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 {
     internal class CancellationDisposable : IDisposable
     {
-        private CancellationTokenSource _cts;
+        private readonly CancellationTokenSource _cts;
 
         public CancellationDisposable(CancellationTokenSource cts)
         {
diff --git a/test/Microsoft.AspNetCore.SignalR.Tests/EndToEndTests.cs b/test/Microsoft.AspNetCore.SignalR.Tests/EndToEndTests.cs
index 38dd0ee325..01c1d5f2b7 100644
--- a/test/Microsoft.AspNetCore.SignalR.Tests/EndToEndTests.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Tests/EndToEndTests.cs
@@ -473,7 +473,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
             private string _prevConnectionId = null;
             private IDuplexPipe _application;
             private IDuplexPipe _transport;
-            private int availableTransports = 3;
+            private readonly int availableTransports = 3;
 
             public PipeReader Input => _transport.Input;
 
diff --git a/test/Microsoft.AspNetCore.SignalR.Tests/HubEndpointTestUtils/Hubs.cs b/test/Microsoft.AspNetCore.SignalR.Tests/HubEndpointTestUtils/Hubs.cs
index 8782293e8c..3d3e4135df 100644
--- a/test/Microsoft.AspNetCore.SignalR.Tests/HubEndpointTestUtils/Hubs.cs
+++ b/test/Microsoft.AspNetCore.SignalR.Tests/HubEndpointTestUtils/Hubs.cs
@@ -498,7 +498,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 
     public class ConnectionLifetimeHub : Hub
     {
-        private ConnectionLifetimeState _state;
+        private readonly ConnectionLifetimeState _state;
 
         public ConnectionLifetimeHub(ConnectionLifetimeState state)
         {