diff --git a/Octokit.Reactive/Clients/ObservableGitHubAppInstallationsClient.cs b/Octokit.Reactive/Clients/ObservableGitHubAppInstallationsClient.cs
index 531aa23aa8..2c575c69a6 100644
--- a/Octokit.Reactive/Clients/ObservableGitHubAppInstallationsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableGitHubAppInstallationsClient.cs
@@ -11,7 +11,7 @@ namespace Octokit.Reactive
     /// </remarks>
     public class ObservableGitHubAppInstallationsClient : IObservableGitHubAppInstallationsClient
     {
-        private IGitHubAppInstallationsClient _client;
+        private readonly IGitHubAppInstallationsClient _client;
         private readonly IConnection _connection;
 
         public ObservableGitHubAppInstallationsClient(IGitHubClient client)
diff --git a/Octokit.Reactive/Clients/ObservableGitHubAppsClient.cs b/Octokit.Reactive/Clients/ObservableGitHubAppsClient.cs
index c3baf089ec..8179baa5de 100644
--- a/Octokit.Reactive/Clients/ObservableGitHubAppsClient.cs
+++ b/Octokit.Reactive/Clients/ObservableGitHubAppsClient.cs
@@ -12,7 +12,7 @@ namespace Octokit.Reactive
     /// </remarks>
     public class ObservableGitHubAppsClient : IObservableGitHubAppsClient
     {
-        private IGitHubAppsClient _client;
+        private readonly IGitHubAppsClient _client;
         private readonly IConnection _connection;
 
         public ObservableGitHubAppsClient(IGitHubClient client)
diff --git a/Octokit.Reactive/ObservableCodespacesClient.cs b/Octokit.Reactive/ObservableCodespacesClient.cs
index 74ce55a872..b8c6575346 100644
--- a/Octokit.Reactive/ObservableCodespacesClient.cs
+++ b/Octokit.Reactive/ObservableCodespacesClient.cs
@@ -5,8 +5,8 @@ namespace Octokit.Reactive
 {
     public class ObservableCodespacesClient : IObservableCodespacesClient
     {
-        private ICodespacesClient _client;
-        private IConnection _connection;
+        private readonly ICodespacesClient _client;
+        private readonly IConnection _connection;
 
         public ObservableCodespacesClient(IGitHubClient githubClient)
         {
diff --git a/Octokit.Tests.Integration/Clients/CheckRunsClientTests.cs b/Octokit.Tests.Integration/Clients/CheckRunsClientTests.cs
index cd10169931..5794088d5e 100644
--- a/Octokit.Tests.Integration/Clients/CheckRunsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/CheckRunsClientTests.cs
@@ -10,8 +10,8 @@ public class CheckRunsClientTests
     {
         public class TheCreateMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheCreateMethod()
             {
@@ -68,8 +68,8 @@ public async Task CreatesCheckRunWithRepositoryId()
 
         public class TheUpdateMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheUpdateMethod()
             {
@@ -146,8 +146,8 @@ public async Task UpdatesCheckRunWithRepositoryId()
 
         public class TheGetAllForReferenceMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetAllForReferenceMethod()
             {
@@ -230,8 +230,8 @@ public async Task GetsAllCheckRunsWithRepositoryId()
 
         public class TheGetAllForCheckSuiteMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetAllForCheckSuiteMethod()
             {
@@ -315,8 +315,8 @@ public async Task GetsAllCheckRunsWithRepositoryId()
 
         public class TheGetMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetMethod()
             {
@@ -383,8 +383,8 @@ public async Task GetsCheckRunWithRepositoryId()
 
         public class TheGetAllAnnotationsMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetAllAnnotationsMethod()
             {
diff --git a/Octokit.Tests.Integration/Clients/CheckSuitesClientTests.cs b/Octokit.Tests.Integration/Clients/CheckSuitesClientTests.cs
index 03be9d99cf..cfdbb9e9e0 100644
--- a/Octokit.Tests.Integration/Clients/CheckSuitesClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/CheckSuitesClientTests.cs
@@ -9,8 +9,8 @@ public class CheckSuitesClientTests
     {
         public class TheGetMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetMethod()
             {
@@ -59,8 +59,8 @@ public async Task GetsCheckSuiteWithRepositoryId()
 
         public class TheGetAllForReferenceMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetAllForReferenceMethod()
             {
@@ -107,8 +107,8 @@ public async Task GetsAllCheckSuitesWithRepositoryId()
 
         public class TheUpdatePreferencesMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheUpdatePreferencesMethod()
             {
@@ -155,8 +155,8 @@ public async Task UpdatesPreferencesWithRepositoryId()
 
         public class TheCreateMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheCreateMethod()
             {
@@ -215,8 +215,8 @@ public async Task CreatesCheckSuiteWithRepositoryId()
 
         public class TheRerequestMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheRerequestMethod()
             {
diff --git a/Octokit.Tests.Integration/Clients/GitHubAppInstallationsClientTests.cs b/Octokit.Tests.Integration/Clients/GitHubAppInstallationsClientTests.cs
index 7260bc3786..7039536e93 100644
--- a/Octokit.Tests.Integration/Clients/GitHubAppInstallationsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/GitHubAppInstallationsClientTests.cs
@@ -8,7 +8,7 @@ public class GitHubAppInstallationsClientTests
     {
         public class TheGetAllRepositoriesForCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetAllRepositoriesForCurrentMethod()
             {
@@ -28,7 +28,7 @@ public async Task GetsAllRepositories()
 
         public class TheGetAllRepositoriesForCurrentUserMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetAllRepositoriesForCurrentUserMethod()
             {
diff --git a/Octokit.Tests.Integration/Clients/GitHubAppsClientTests.cs b/Octokit.Tests.Integration/Clients/GitHubAppsClientTests.cs
index 7a26b714b1..e5f97e77ef 100644
--- a/Octokit.Tests.Integration/Clients/GitHubAppsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/GitHubAppsClientTests.cs
@@ -9,7 +9,7 @@ public class GitHubAppsClientTests
     {
         public class TheGetMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetMethod()
             {
@@ -31,7 +31,7 @@ public async Task GetsApp()
 
         public class TheGetCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetCurrentMethod()
             {
@@ -53,7 +53,7 @@ public async Task GetsCurrentApp()
 
         public class TheGetAllInstallationsForCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetAllInstallationsForCurrentMethod()
             {
@@ -80,7 +80,7 @@ public async Task GetsAllInstallations()
 
         public class TheGetInstallationForCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetInstallationForCurrentMethod()
             {
@@ -109,7 +109,7 @@ public async Task GetsInstallation()
 
         public class TheGetAllInstallationsForCurrentUserMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetAllInstallationsForCurrentUserMethod()
             {
@@ -130,7 +130,7 @@ public async Task GetsAllInstallationsForCurrentUser()
 
         public class TheCreateInstallationTokenMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheCreateInstallationTokenMethod()
             {
@@ -154,7 +154,7 @@ public async Task CreatesInstallationToken()
 
         public class TheGetOrganizationInstallationForCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetOrganizationInstallationForCurrentMethod()
             {
@@ -173,8 +173,8 @@ public async Task GetsOrganizationInstallations()
 
         public class TheGetRepositoryInstallationForCurrentMethod
         {
-            IGitHubClient _github;
-            IGitHubClient _githubAppInstallation;
+            readonly IGitHubClient _github;
+            readonly IGitHubClient _githubAppInstallation;
 
             public TheGetRepositoryInstallationForCurrentMethod()
             {
@@ -214,7 +214,7 @@ public async Task GetsRepositoryInstallationsWithRepositoryId()
 
         public class TheGetUserInstallationForCurrentMethod
         {
-            IGitHubClient _github;
+            readonly IGitHubClient _github;
 
             public TheGetUserInstallationForCurrentMethod()
             {
diff --git a/Octokit.Tests.Integration/Clients/MigrationsClientTests.cs b/Octokit.Tests.Integration/Clients/MigrationsClientTests.cs
index 8b868d2c00..4e6298c919 100644
--- a/Octokit.Tests.Integration/Clients/MigrationsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/MigrationsClientTests.cs
@@ -11,9 +11,9 @@
 public class MigrationsClientTests : IDisposable
 {
     private readonly IGitHubClient _gitHub;
-    private List<RepositoryContext> _repos;
+    private readonly List<RepositoryContext> _repos;
     private Migration _migrationContext;
-    private string _orgName;
+    private readonly string _orgName;
     private bool isExported = false;
 
     public MigrationsClientTests()
diff --git a/Octokit.Tests.Integration/Clients/OrganizationMembersClientTests.cs b/Octokit.Tests.Integration/Clients/OrganizationMembersClientTests.cs
index 16f0f8cf5d..d1fcb7f2c9 100644
--- a/Octokit.Tests.Integration/Clients/OrganizationMembersClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/OrganizationMembersClientTests.cs
@@ -9,8 +9,8 @@ public class OrganizationMembersClientTests
     {
         public class TheGetAllMethod
         {
-            private IGitHubClient _gitHub;
-            private string _organizationFixture;
+            private readonly IGitHubClient _gitHub;
+            private readonly string _organizationFixture;
 
             public TheGetAllMethod()
             {
@@ -296,7 +296,7 @@ public async Task ReturnsNoFailedInvitations()
 
         public class TheGetAllOrganizationMembershipsForCurrentMethod
         {
-            private IGitHubClient _gitHub;
+            private readonly IGitHubClient _gitHub;
 
             public TheGetAllOrganizationMembershipsForCurrentMethod()
             {
diff --git a/Octokit.Tests.Integration/Clients/ProjectCardsClientTests.cs b/Octokit.Tests.Integration/Clients/ProjectCardsClientTests.cs
index 97568ead56..8607eb068f 100644
--- a/Octokit.Tests.Integration/Clients/ProjectCardsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/ProjectCardsClientTests.cs
@@ -9,8 +9,8 @@ public class ProjectCardsClientTests
 {
     public class TheGetAllMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllMethod()
         {
@@ -164,8 +164,8 @@ public void Dispose()
 
     public class TheGetMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetMethod()
         {
@@ -196,8 +196,8 @@ public void Dispose()
 
     public class TheCreateMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheCreateMethod()
         {
@@ -252,8 +252,8 @@ public void Dispose()
 
     public class TheUpdateMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateMethod()
         {
@@ -325,8 +325,8 @@ public void Dispose()
 
     public class TheDeleteMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteMethod()
         {
@@ -357,8 +357,8 @@ public void Dispose()
 
     public class TheMoveMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheMoveMethod()
         {
diff --git a/Octokit.Tests.Integration/Clients/ProjectColumnsClientTests.cs b/Octokit.Tests.Integration/Clients/ProjectColumnsClientTests.cs
index a8bfe67da1..c7843d797f 100644
--- a/Octokit.Tests.Integration/Clients/ProjectColumnsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/ProjectColumnsClientTests.cs
@@ -11,8 +11,8 @@ public class ProjectColumnsClientTests
 {
     public class TheGetAllColumnsMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllColumnsMethod()
         {
@@ -111,8 +111,8 @@ public void Dispose()
 
     public class TheGetColumnMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetColumnMethod()
         {
@@ -142,8 +142,8 @@ public void Dispose()
 
     public class TheCreateColumnMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheCreateColumnMethod()
         {
@@ -171,8 +171,8 @@ public void Dispose()
 
     public class TheUpdateColumnMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateColumnMethod()
         {
@@ -205,8 +205,8 @@ public void Dispose()
 
     public class TheDeleteColumnMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteColumnMethod()
         {
@@ -236,8 +236,8 @@ public void Dispose()
 
     public class TheMoveColumnMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheMoveColumnMethod()
         {
diff --git a/Octokit.Tests.Integration/Clients/ProjectsClientTests.cs b/Octokit.Tests.Integration/Clients/ProjectsClientTests.cs
index 1f20a2abe9..4d82149e3c 100644
--- a/Octokit.Tests.Integration/Clients/ProjectsClientTests.cs
+++ b/Octokit.Tests.Integration/Clients/ProjectsClientTests.cs
@@ -11,8 +11,8 @@ public class ProjectsClientTests
 {
     public class TheGetAllForRepositoryMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllForRepositoryMethod()
         {
@@ -213,7 +213,7 @@ public void Dispose()
 
     public class TheGetAllForOrganizationMethod
     {
-        IGitHubClient _github;
+        readonly IGitHubClient _github;
 
         public TheGetAllForOrganizationMethod()
         {
@@ -286,8 +286,8 @@ public async Task ReturnsDistinctProjectsForOrganizationBasedOnStartPage()
 
     public class TheGetMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetMethod()
         {
@@ -317,8 +317,8 @@ public void Dispose()
 
     public class TheUpdateMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateMethod()
         {
@@ -355,8 +355,8 @@ public void Dispose()
 
     public class TheDeleteMethod : IDisposable
     {
-        IGitHubClient _github;
-        RepositoryContext _context;
+        readonly IGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteMethod()
         {
diff --git a/Octokit.Tests.Integration/Helpers/EnterpriseUserContext.cs b/Octokit.Tests.Integration/Helpers/EnterpriseUserContext.cs
index 177a8c6902..e2c37b4e8c 100644
--- a/Octokit.Tests.Integration/Helpers/EnterpriseUserContext.cs
+++ b/Octokit.Tests.Integration/Helpers/EnterpriseUserContext.cs
@@ -17,7 +17,7 @@ internal EnterpriseUserContext(IConnection connection, User user)
             UserEmail = user.Email;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int UserId { get; private set; }
         internal string UserLogin { get; private set; }
         internal string UserEmail { get; private set; }
diff --git a/Octokit.Tests.Integration/Helpers/GpgKeyContext.cs b/Octokit.Tests.Integration/Helpers/GpgKeyContext.cs
index bb85369a4f..fd141d3ada 100644
--- a/Octokit.Tests.Integration/Helpers/GpgKeyContext.cs
+++ b/Octokit.Tests.Integration/Helpers/GpgKeyContext.cs
@@ -17,7 +17,7 @@ internal GpgKeyContext(IConnection connection, GpgKey key)
             PublicKeyData = key.PublicKey;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int GpgKeyId { get; set; }
         internal string KeyId { get; set; }
         internal string PublicKeyData { get; set; }
diff --git a/Octokit.Tests.Integration/Helpers/MaintenanceModeContext.cs b/Octokit.Tests.Integration/Helpers/MaintenanceModeContext.cs
index 26c405356a..f318f8d302 100644
--- a/Octokit.Tests.Integration/Helpers/MaintenanceModeContext.cs
+++ b/Octokit.Tests.Integration/Helpers/MaintenanceModeContext.cs
@@ -17,7 +17,7 @@ internal MaintenanceModeContext(IConnection connection, bool enabled)
             EnterpriseHelper.SetMaintenanceMode(_connection, enabled);
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
 
         public void Dispose()
         {
diff --git a/Octokit.Tests.Integration/Helpers/PublicKeyContext.cs b/Octokit.Tests.Integration/Helpers/PublicKeyContext.cs
index bf4b2d3292..0de57597ab 100644
--- a/Octokit.Tests.Integration/Helpers/PublicKeyContext.cs
+++ b/Octokit.Tests.Integration/Helpers/PublicKeyContext.cs
@@ -17,7 +17,7 @@ internal PublicKeyContext(IConnection connection, PublicKey key)
             KeyData = key.Key;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int KeyId { get; private set; }
         internal string KeyTitle { get; private set; }
         internal string KeyData { get; private set; }
diff --git a/Octokit.Tests.Integration/Helpers/RepositoryContext.cs b/Octokit.Tests.Integration/Helpers/RepositoryContext.cs
index 35f62931d2..1513e6ad5d 100644
--- a/Octokit.Tests.Integration/Helpers/RepositoryContext.cs
+++ b/Octokit.Tests.Integration/Helpers/RepositoryContext.cs
@@ -19,7 +19,7 @@ internal RepositoryContext(IConnection connection, Repository repo)
             RepositoryDefaultBranch = repo.DefaultBranch;
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal long RepositoryId { get; private set; }
         internal string RepositoryOwner { get; private set; }
         internal string RepositoryName { get; private set; }
diff --git a/Octokit.Tests.Integration/Helpers/TeamContext.cs b/Octokit.Tests.Integration/Helpers/TeamContext.cs
index f4cc15a26b..2785b618f8 100644
--- a/Octokit.Tests.Integration/Helpers/TeamContext.cs
+++ b/Octokit.Tests.Integration/Helpers/TeamContext.cs
@@ -15,7 +15,7 @@ internal TeamContext(IConnection connection, Team team)
             Invitations = new List<string>();
         }
 
-        private IConnection _connection;
+        private readonly IConnection _connection;
         internal int TeamId { get; private set; }
         internal string TeamName { get; private set; }
 
diff --git a/Octokit.Tests.Integration/Reactive/ObservableCheckRunsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableCheckRunsClientTests.cs
index dad48855c9..25f2f150aa 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableCheckRunsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableCheckRunsClientTests.cs
@@ -12,8 +12,8 @@ public class ObservableCheckRunsClientTests
     {
         public class TheCreateMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheCreateMethod()
             {
@@ -70,8 +70,8 @@ public async Task CreatesCheckRunWithRepositoryId()
 
         public class TheUpdateMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheUpdateMethod()
             {
@@ -148,8 +148,8 @@ public async Task UpdatesCheckRunWithRepositoryId()
 
         public class TheGetAllForReferenceMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetAllForReferenceMethod()
             {
@@ -232,8 +232,8 @@ public async Task GetsAllCheckRunsWithRepositoryId()
 
         public class TheGetAllForCheckSuiteMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetAllForCheckSuiteMethod()
             {
@@ -316,8 +316,8 @@ public async Task GetsAllCheckRunsWithRepositoryId()
 
         public class TheGetMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetMethod()
             {
@@ -384,8 +384,8 @@ public async Task GetsCheckRunWithRepositoryId()
 
         public class TheGetAllAnnotationsMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetAllAnnotationsMethod()
             {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableCheckSuitesClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableCheckSuitesClientTests.cs
index b9b44c28f8..b210c022fb 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableCheckSuitesClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableCheckSuitesClientTests.cs
@@ -11,8 +11,8 @@ public class ObservableCheckSuitesClientTests
     {
         public class TheGetMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetMethod()
             {
@@ -61,8 +61,8 @@ public async Task GetsCheckSuiteWithRepositoryId()
 
         public class TheGetAllForReferenceMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetAllForReferenceMethod()
             {
@@ -109,8 +109,8 @@ public async Task GetsAllCheckSuitesWithRepositoryId()
 
         public class TheUpdatePreferencesMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheUpdatePreferencesMethod()
             {
@@ -157,8 +157,8 @@ public async Task UpdatesPreferencesWithRepositoryId()
 
         public class TheCreateMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheCreateMethod()
             {
@@ -217,8 +217,8 @@ public async Task CreatesCheckSuiteWithRepositoryId()
 
         public class TheRerequestMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheRerequestMethod()
             {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableGitHubAppInstallationsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableGitHubAppInstallationsClientTests.cs
index 41609fa0eb..5c0a47befa 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableGitHubAppInstallationsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableGitHubAppInstallationsClientTests.cs
@@ -10,7 +10,7 @@ public class ObservableGitHubAppInstallationsClientTests
     {
         public class TheGetAllRepositoriesForCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetAllRepositoriesForCurrentMethod()
             {
@@ -30,7 +30,7 @@ public async Task GetsAllRepositories()
 
         public class TheGetAllRepositoriesForCurrentUserMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetAllRepositoriesForCurrentUserMethod()
             {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableGitHubAppsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableGitHubAppsClientTests.cs
index f5da91a3de..3cc2c7b30a 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableGitHubAppsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableGitHubAppsClientTests.cs
@@ -11,7 +11,7 @@ public class ObservableGitHubAppsClientTests
     {
         public class TheGetMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetMethod()
             {
@@ -33,7 +33,7 @@ public async Task GetsApp()
 
         public class TheGetCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetCurrentMethod()
             {
@@ -55,7 +55,7 @@ public async Task GetsCurrentApp()
 
         public class TheGetAllInstallationsForCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetAllInstallationsForCurrentMethod()
             {
@@ -82,7 +82,7 @@ public async Task GetsAllInstallations()
 
         public class TheGetInstallationForCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetInstallationForCurrentMethod()
             {
@@ -111,7 +111,7 @@ public async Task GetsInstallation()
 
         public class TheGetAllInstallationsForCurrentUserMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetAllInstallationsForCurrentUserMethod()
             {
@@ -132,7 +132,7 @@ public async Task GetsAllInstallationsForCurrentUser()
 
         public class TheCreateInstallationTokenMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheCreateInstallationTokenMethod()
             {
@@ -156,7 +156,7 @@ public async Task CreatesInstallationToken()
 
         public class TheGetOrganizationInstallationForCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetOrganizationInstallationForCurrentMethod()
             {
@@ -175,8 +175,8 @@ public async Task GetsOrganizationInstallations()
 
         public class TheGetRepositoryInstallationForCurrentMethod
         {
-            IObservableGitHubClient _github;
-            IObservableGitHubClient _githubAppInstallation;
+            readonly IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _githubAppInstallation;
 
             public TheGetRepositoryInstallationForCurrentMethod()
             {
@@ -216,7 +216,7 @@ public async Task GetsRepositoryInstallationsWithRepositoryId()
 
         public class TheGetUserInstallationForCurrentMethod
         {
-            IObservableGitHubClient _github;
+            readonly IObservableGitHubClient _github;
 
             public TheGetUserInstallationForCurrentMethod()
             {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableProjectCardsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableProjectCardsClientTests.cs
index d3f29dbaea..7eeb51957e 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableProjectCardsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableProjectCardsClientTests.cs
@@ -12,8 +12,8 @@ public class ObservableProjectCardsClientTests
 {
     public class TheGetAllMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllMethod()
         {
@@ -167,8 +167,8 @@ public void Dispose()
 
     public class TheGetMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetMethod()
         {
@@ -199,8 +199,8 @@ public void Dispose()
 
     public class TheCreateMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheCreateMethod()
         {
@@ -240,8 +240,8 @@ public void Dispose()
 
     public class TheUpdateMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateMethod()
         {
@@ -313,8 +313,8 @@ public void Dispose()
 
     public class TheDeleteMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteMethod()
         {
@@ -345,8 +345,8 @@ public void Dispose()
 
     public class TheMoveMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheMoveMethod()
         {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableProjectColumnsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableProjectColumnsClientTests.cs
index fe9e5e257a..5bf5214940 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableProjectColumnsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableProjectColumnsClientTests.cs
@@ -13,8 +13,8 @@ public class ObservableProjectColumnsClientTests
 {
     public class TheGetAllColumnsMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllColumnsMethod()
         {
@@ -113,8 +113,8 @@ public void Dispose()
 
     public class TheGetColumnMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetColumnMethod()
         {
@@ -144,8 +144,8 @@ public void Dispose()
 
     public class TheCreateColumnMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheCreateColumnMethod()
         {
@@ -173,8 +173,8 @@ public void Dispose()
 
     public class TheUpdateColumnMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateColumnMethod()
         {
@@ -207,8 +207,8 @@ public void Dispose()
 
     public class TheDeleteColumnMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteColumnMethod()
         {
@@ -238,8 +238,8 @@ public void Dispose()
 
     public class TheMoveColumnMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheMoveColumnMethod()
         {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableProjectsClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableProjectsClientTests.cs
index c9fc202457..bdb39975d3 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableProjectsClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableProjectsClientTests.cs
@@ -13,8 +13,8 @@ public class ObservableProjectsClientTests
 {
     public class TheGetAllForRepositoryMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetAllForRepositoryMethod()
         {
@@ -215,7 +215,7 @@ public void Dispose()
 
     public class TheGetAllForOrganizationMethod
     {
-        IObservableGitHubClient _github;
+        readonly IObservableGitHubClient _github;
 
         public TheGetAllForOrganizationMethod()
         {
@@ -288,8 +288,8 @@ public async Task ReturnsDistinctProjectsForOrganizationBasedOnStartPage()
 
     public class TheGetMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheGetMethod()
         {
@@ -319,8 +319,8 @@ public void Dispose()
 
     public class TheUpdateMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheUpdateMethod()
         {
@@ -357,8 +357,8 @@ public void Dispose()
 
     public class TheDeleteMethod : IDisposable
     {
-        IObservableGitHubClient _github;
-        RepositoryContext _context;
+        readonly IObservableGitHubClient _github;
+        readonly RepositoryContext _context;
 
         public TheDeleteMethod()
         {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableRepositoryBranchesClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableRepositoryBranchesClientTests.cs
index 808a84217c..d35a4e8db7 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableRepositoryBranchesClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableRepositoryBranchesClientTests.cs
@@ -10,8 +10,8 @@ public class ObservableRepositoryBranchesClientTests
     {
         public class TheGetBranchProtectionMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheGetBranchProtectionMethod()
             {
@@ -116,8 +116,8 @@ public async Task GetsBranchProtectionForOrgRepoWithRepositoryId()
 
         public class TheUpdateBranchProtectionMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheUpdateBranchProtectionMethod()
             {
@@ -262,8 +262,8 @@ public async Task UpdatesBranchProtectionForOrgRepoWithRepositoryId()
 
         public class TheDeleteBranchProtectionMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheDeleteBranchProtectionMethod()
             {
@@ -324,8 +324,8 @@ public async Task DeletesBranchProtectionForOrgRepoWithRepositoryId()
 
         public class TheGetReviewEnforcementMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheGetReviewEnforcementMethod()
             {
@@ -396,8 +396,8 @@ public async Task GetsReviewEnforcementForOrgRepoWithRepositoryId()
 
         public class TheUpdateReviewEnforcementMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheUpdateReviewEnforcementMethod()
             {
@@ -530,8 +530,8 @@ public async Task UpdatesReviewEnforcementForOrgRepoWithAdminOnlyWithRepositoryI
 
         public class TheRemoveReviewEnforcementMethod
         {
-            IGitHubClient _github;
-            IObservableRepositoryBranchesClient _client;
+            readonly IGitHubClient _github;
+            readonly IObservableRepositoryBranchesClient _client;
 
             public TheRemoveReviewEnforcementMethod()
             {
diff --git a/Octokit.Tests.Integration/Reactive/ObservableRepositoryDeployKeysClientTests.cs b/Octokit.Tests.Integration/Reactive/ObservableRepositoryDeployKeysClientTests.cs
index 5a6ba833c6..cb0364ce58 100644
--- a/Octokit.Tests.Integration/Reactive/ObservableRepositoryDeployKeysClientTests.cs
+++ b/Octokit.Tests.Integration/Reactive/ObservableRepositoryDeployKeysClientTests.cs
@@ -10,9 +10,9 @@ public class ObservableRespositoryDeployKeysClientTests : IDisposable
 {
     const string _key = "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDB8IE5+RppLpeW+6lqo0fpfvMunKg6W4bhYCfVJIOYbpKoHP95nTUMZPBT++9NLeB4/YsuNTCrrpnpjc4f2IVpGvloRiVXjAzoJk9QIL6uzn1zRFdvaxSJ3Urhe9LcLHcIgccgZgSdWGzaZI3xtMvGC4diwWNsPjvVc/RyDM/MPqAim0X5XVOQwEFsSsUSraezJ+VgYMYzLYBcKWW0B86HVVhL4ZtmcY/RN2544bljnzw2M3aQvXNPTvkuiUoqLOI+5/qzZ8PfkruO55YtweEd0lkY6oZvrBPMD6dLODEqMHb4tD6htx60wSipNqjPwpOMpzp0Bk3G909unVXi6Fw5";
     const string _keyTitle = "octokit@github";
-    ObservableRepositoryDeployKeysClient _client;
-    Repository _repository;
-    string _owner;
+    readonly ObservableRepositoryDeployKeysClient _client;
+    readonly Repository _repository;
+    readonly string _owner;
 
     public ObservableRespositoryDeployKeysClientTests()
     {
diff --git a/Octokit/Http/SimpleJsonSerializer.cs b/Octokit/Http/SimpleJsonSerializer.cs
index b4bb555828..8d6d26e270 100644
--- a/Octokit/Http/SimpleJsonSerializer.cs
+++ b/Octokit/Http/SimpleJsonSerializer.cs
@@ -35,7 +35,7 @@ internal static object DeserializeEnum(string value, Type type)
         class GitHubSerializerStrategy : PocoJsonSerializerStrategy
         {
             readonly List<string> _membersWhichShouldPublishNull = new List<string>();
-            ConcurrentDictionary<Type, ConcurrentDictionary<object, object>> _cachedEnums = new ConcurrentDictionary<Type, ConcurrentDictionary<object, object>>();
+            readonly ConcurrentDictionary<Type, ConcurrentDictionary<object, object>> _cachedEnums = new ConcurrentDictionary<Type, ConcurrentDictionary<object, object>>();
 
             protected override string MapClrMemberToJsonFieldName(MemberInfo member)
             {
diff --git a/Octokit/Models/Request/ApiOptions.cs b/Octokit/Models/Request/ApiOptions.cs
index 3dbfd1d40a..5a3cdb0163 100644
--- a/Octokit/Models/Request/ApiOptions.cs
+++ b/Octokit/Models/Request/ApiOptions.cs
@@ -7,7 +7,7 @@ namespace Octokit
     [DebuggerDisplay("{DebuggerDisplay,nq}")]
     public class ApiOptions
     {
-        private static ApiOptions emptyOptions = new ApiOptions();
+        private static readonly ApiOptions emptyOptions = new ApiOptions();
 
         public static ApiOptions None
         {