diff --git a/Lombiq.Hosting.Tenants.Admin.Login/Controllers/TenantLoginController.cs b/Lombiq.Hosting.Tenants.Admin.Login/Controllers/TenantLoginController.cs
index ed086af8..d7a7afc3 100644
--- a/Lombiq.Hosting.Tenants.Admin.Login/Controllers/TenantLoginController.cs
+++ b/Lombiq.Hosting.Tenants.Admin.Login/Controllers/TenantLoginController.cs
@@ -50,6 +50,8 @@ public TenantLoginController(
     [IgnoreAntiforgeryToken]
     public async Task<IActionResult> Index(string password)
     {
+        if (!ModelState.IsValid) return BadRequest(ModelState);
+
         if (_shellSettings.Name.EqualsOrdinalIgnoreCase(ShellSettings.DefaultShellName))
         {
             return NotFound();
diff --git a/Lombiq.Hosting.Tenants.Admin.Login/Permissions/TenantAdminPermissions.cs b/Lombiq.Hosting.Tenants.Admin.Login/Permissions/TenantAdminPermissions.cs
index dde2abad..823d71ea 100644
--- a/Lombiq.Hosting.Tenants.Admin.Login/Permissions/TenantAdminPermissions.cs
+++ b/Lombiq.Hosting.Tenants.Admin.Login/Permissions/TenantAdminPermissions.cs
@@ -9,5 +9,5 @@ public class TenantAdminPermissions : AdminPermissionBase
     public static readonly Permission LoginAsAdmin =
         new(nameof(LoginAsAdmin), "Able to login as an admin to any tenant from the Default tenant.");
 
-    protected override IEnumerable<Permission> AdminPermissions => new[] { LoginAsAdmin };
+    protected override IEnumerable<Permission> AdminPermissions => [LoginAsAdmin];
 }
diff --git a/Lombiq.Hosting.Tenants.FeaturesGuard/Extensions/OrchardCoreBuilderExtensions.cs b/Lombiq.Hosting.Tenants.FeaturesGuard/Extensions/OrchardCoreBuilderExtensions.cs
index 643d9c56..0b56d389 100644
--- a/Lombiq.Hosting.Tenants.FeaturesGuard/Extensions/OrchardCoreBuilderExtensions.cs
+++ b/Lombiq.Hosting.Tenants.FeaturesGuard/Extensions/OrchardCoreBuilderExtensions.cs
@@ -14,7 +14,7 @@ public static OrchardCoreBuilder ConfigureFeaturesGuardForAzureStorage(this Orch
         builder.ConfigureFeaturesGuardWithoutOverriding(
             new Dictionary<string, IEnumerable<string>>
             {
-                ["OrchardCore.Media.Azure.Storage"] = new List<string> { "OrchardCore.Media" },
+                ["OrchardCore.Media.Azure.Storage"] = ["OrchardCore.Media"],
             });
 
     /// <summary>
@@ -26,7 +26,7 @@ public static OrchardCoreBuilder ConfigureFeaturesGuardForElasticsearch(this Orc
             new Dictionary<string, IEnumerable<string>>
             {
                 ["OrchardCore.Search.Elasticsearch"] =
-                    new List<string> { "OrchardCore.Search", "OrchardCore.Indexing" },
+                    ["OrchardCore.Search", "OrchardCore.Indexing"],
             });
 
     /// <summary>
@@ -37,7 +37,7 @@ public static OrchardCoreBuilder ConfigureFeaturesGuardForEmailQuota(this Orchar
         builder.ConfigureFeaturesGuardWithoutOverriding(
             new Dictionary<string, IEnumerable<string>>
             {
-                ["Lombiq.Hosting.Tenants.EmailQuotaManagement"] = new List<string> { "OrchardCore.Email" },
+                ["Lombiq.Hosting.Tenants.EmailQuotaManagement"] = ["OrchardCore.Email"],
             });
 
     /// <summary>
diff --git a/Lombiq.Hosting.Tenants.Management/Controllers/ShellSettingsEditorController.cs b/Lombiq.Hosting.Tenants.Management/Controllers/ShellSettingsEditorController.cs
index 4e0d9a0a..b765382b 100644
--- a/Lombiq.Hosting.Tenants.Management/Controllers/ShellSettingsEditorController.cs
+++ b/Lombiq.Hosting.Tenants.Management/Controllers/ShellSettingsEditorController.cs
@@ -46,6 +46,8 @@ public ShellSettingsEditorController(
     [ValidateAntiForgeryToken]
     public async Task<IActionResult> Edit(ShellSettingsEditorViewModel model)
     {
+        if (!ModelState.IsValid) return BadRequest(ModelState);
+
         if (!await _authorizationService.AuthorizeAsync(User, ManageTenants) ||
             !_shellHost.TryGetSettings(model.TenantId, out var shellSettings))
         {
diff --git a/Lombiq.Hosting.Tenants.Management/Settings/HideRecipesFromSetupOptions.cs b/Lombiq.Hosting.Tenants.Management/Settings/HideRecipesFromSetupOptions.cs
index 677610dd..2e5f229e 100644
--- a/Lombiq.Hosting.Tenants.Management/Settings/HideRecipesFromSetupOptions.cs
+++ b/Lombiq.Hosting.Tenants.Management/Settings/HideRecipesFromSetupOptions.cs
@@ -5,5 +5,5 @@ namespace Lombiq.Hosting.Tenants.Management.Settings;
 
 public class HideRecipesFromSetupOptions
 {
-    public IEnumerable<string> HiddenTags { get; set; } = new[] { HideFromSetupScreen };
+    public IEnumerable<string> HiddenTags { get; set; } = [HideFromSetupScreen];
 }