diff --git a/Fronter.NET/Extensions/NotificationMessageBuilderExtensions.cs b/Fronter.NET/Extensions/NotificationMessageBuilderExtensions.cs
index 5f62f68a..31c331f1 100644
--- a/Fronter.NET/Extensions/NotificationMessageBuilderExtensions.cs
+++ b/Fronter.NET/Extensions/NotificationMessageBuilderExtensions.cs
@@ -5,7 +5,7 @@
 
 namespace Fronter.Extensions;
 
-public static class NotificationMessageBuilderExtensions {
+internal static class NotificationMessageBuilderExtensions {
 	public static NotificationMessageBuilder CreateError(this INotificationMessageManager manager) {
 		return manager
 			.CreateMessage()
diff --git a/Fronter.NET/Extensions/TranslationSource.cs b/Fronter.NET/Extensions/TranslationSource.cs
index 290602b3..7e114725 100644
--- a/Fronter.NET/Extensions/TranslationSource.cs
+++ b/Fronter.NET/Extensions/TranslationSource.cs
@@ -10,7 +10,7 @@
 namespace Fronter.Extensions;
 
 // idea based on https://gist.github.com/jakubfijalkowski/0771bfbd26ce68456d3e
-public sealed partial class TranslationSource : ReactiveObject {
+internal sealed partial class TranslationSource : ReactiveObject {
 	private static readonly ILog logger = LogManager.GetLogger("Translator");
 	private TranslationSource() {
 		const string languagesPath = "languages.txt";
@@ -148,7 +148,7 @@ private void LoadLanguages() {
 		}
 	}
 
-	public IList<string> LoadedLanguages { get; } = [];
+	public List<string> LoadedLanguages { get; } = [];
 	private readonly Dictionary<string, CultureInfo> languages = [];
 	private readonly Dictionary<string, Dictionary<string, string>> translations = []; // key, <language, text>
 
diff --git a/Fronter.NET/Fronter.csproj b/Fronter.NET/Fronter.csproj
index abd80b23..95207ce3 100644
--- a/Fronter.NET/Fronter.csproj
+++ b/Fronter.NET/Fronter.csproj
@@ -95,4 +95,8 @@
     <ItemGroup>
       <Folder Include="Models\Database\" />
     </ItemGroup>
+
+    <ItemGroup>
+        <InternalsVisibleTo Include="Fronter.Tests"/>
+    </ItemGroup>
 </Project>
diff --git a/Fronter.NET/Models/Configuration/Config.cs b/Fronter.NET/Models/Configuration/Config.cs
index a84fb801..fac6b8bf 100644
--- a/Fronter.NET/Models/Configuration/Config.cs
+++ b/Fronter.NET/Models/Configuration/Config.cs
@@ -11,7 +11,7 @@
 
 namespace Fronter.Models.Configuration;
 
-public sealed class Config {
+internal sealed class Config {
 	public string Name { get; private set; } = string.Empty;
 	public string ConverterFolder { get; private set; } = string.Empty;
 	public string BackendExePath { get; private set; } = string.Empty; // relative to ConverterFolder
@@ -28,9 +28,9 @@ public sealed class Config {
 	public string ConverterReleaseForumThread { get; private set; } = string.Empty;
 	public string LatestGitHubConverterReleaseUrl { get; private set; } = string.Empty;
 	public string PagesCommitIdUrl { get; private set; } = string.Empty;
-	public IList<RequiredFile> RequiredFiles { get; } = new List<RequiredFile>();
-	public IList<RequiredFolder> RequiredFolders { get; } = new List<RequiredFolder>();
-	public IList<Option> Options { get; } = new List<Option>();
+	public List<RequiredFile> RequiredFiles { get; } = [];
+	public List<RequiredFolder> RequiredFolders { get; } = [];
+	public List<Option> Options { get; } = [];
 	private int optionCounter;
 
 	private static readonly ILog logger = LogManager.GetLogger("Configuration");
diff --git a/Fronter.NET/Models/Configuration/Options/CheckBoxSelector.cs b/Fronter.NET/Models/Configuration/Options/CheckBoxSelector.cs
index 7e192a7d..3be128c2 100644
--- a/Fronter.NET/Models/Configuration/Options/CheckBoxSelector.cs
+++ b/Fronter.NET/Models/Configuration/Options/CheckBoxSelector.cs
@@ -5,7 +5,7 @@
 
 namespace Fronter.Models.Configuration.Options;
 
-public sealed class CheckBoxSelector {
+internal sealed class CheckBoxSelector {
 	public CheckBoxSelector(BufferedReader reader) {
 		var parser = new Parser();
 		RegisterKeys(parser);
@@ -20,7 +20,7 @@ private void RegisterKeys(Parser parser) {
 		parser.RegisterRegex(CommonRegexes.Catchall, ParserHelpers.IgnoreAndLogItem);
 	}
 
-	public ISet<string> GetSelectedValues() {
+	public HashSet<string> GetSelectedValues() {
 		var toReturn = new HashSet<string>(StringComparer.Ordinal);
 		foreach (ToggleableOption option in CheckBoxOptions.Where(option => option.Value)) {
 			toReturn.Add(option.Name);
@@ -28,7 +28,7 @@ public ISet<string> GetSelectedValues() {
 		return toReturn;
 	}
 
-	public ISet<int> GetSelectedIds() {
+	public HashSet<int> GetSelectedIds() {
 		var toReturn = new HashSet<int>();
 		foreach (ToggleableOption option in CheckBoxOptions.Where(option => option.Value)) {
 			toReturn.Add(option.Id);
@@ -49,5 +49,5 @@ public void SetSelectedValues(ISet<string> selection) {
 
 	private int optionCounter = 0;
 	public bool Preloaded { get; set; } = false;
-	public IList<ToggleableOption> CheckBoxOptions { get; } = new List<ToggleableOption>();
+	public List<ToggleableOption> CheckBoxOptions { get; } = [];
 }
\ No newline at end of file
diff --git a/Fronter.NET/Models/Configuration/Options/Option.cs b/Fronter.NET/Models/Configuration/Options/Option.cs
index f1a7acb8..a7292695 100644
--- a/Fronter.NET/Models/Configuration/Options/Option.cs
+++ b/Fronter.NET/Models/Configuration/Options/Option.cs
@@ -5,7 +5,7 @@
 
 namespace Fronter.Models.Configuration.Options;
 
-public sealed class Option {
+internal sealed class Option {
 	private static readonly ILog logger = LogManager.GetLogger("Option");
 	public Option(BufferedReader reader, int id) {
 		Id = id;
@@ -78,7 +78,7 @@ public string GetValue() {
 		return string.Empty;
 	}
 
-	public ISet<string> GetValues() {
+	public HashSet<string> GetValues() {
 		return CheckBoxSelector is not null
 			? CheckBoxSelector.GetSelectedValues()
 			: new HashSet<string>(StringComparer.Ordinal);
diff --git a/Fronter.NET/Models/Configuration/Options/RadioSelector.cs b/Fronter.NET/Models/Configuration/Options/RadioSelector.cs
index e33d2470..e32c2cec 100644
--- a/Fronter.NET/Models/Configuration/Options/RadioSelector.cs
+++ b/Fronter.NET/Models/Configuration/Options/RadioSelector.cs
@@ -5,7 +5,7 @@
 
 namespace Fronter.Models.Configuration.Options;
 
-public sealed class RadioSelector {
+internal sealed class RadioSelector {
 	private static readonly ILog logger = LogManager.GetLogger("Radio selector");
 	public RadioSelector(BufferedReader reader) {
 		var parser = new Parser();
@@ -71,5 +71,5 @@ public ToggleableOption? SelectedOption {
 	}
 
 	private int optionCounter = 0;
-	public IList<ToggleableOption> RadioOptions { get; } = new List<ToggleableOption>();
+	public List<ToggleableOption> RadioOptions { get; } = [];
 }
\ No newline at end of file
diff --git a/Fronter.NET/Models/Configuration/RequiredFolder.cs b/Fronter.NET/Models/Configuration/RequiredFolder.cs
index f2350683..03b3006f 100644
--- a/Fronter.NET/Models/Configuration/RequiredFolder.cs
+++ b/Fronter.NET/Models/Configuration/RequiredFolder.cs
@@ -7,7 +7,7 @@
 
 namespace Fronter.Models.Configuration;
 
-public sealed class RequiredFolder : RequiredPath {
+internal sealed class RequiredFolder : RequiredPath {
 	private static readonly ILog logger = LogManager.GetLogger("Required folder");
 	public RequiredFolder(BufferedReader reader, Config config) {
 		this.config = config;
diff --git a/Fronter.NET/Services/SentryHelper.cs b/Fronter.NET/Services/SentryHelper.cs
index 9f570a5e..3a116bd4 100644
--- a/Fronter.NET/Services/SentryHelper.cs
+++ b/Fronter.NET/Services/SentryHelper.cs
@@ -11,7 +11,7 @@
 
 namespace Fronter.Services;
 
-public sealed class SentryHelper {
+internal sealed class SentryHelper {
 	public SentryHelper(Config config) {
 		this.config = config;
 		InitSentry();
diff --git a/Fronter.NET/Services/UpdateChecker.cs b/Fronter.NET/Services/UpdateChecker.cs
index 9bc84e75..b3ba8a4c 100644
--- a/Fronter.NET/Services/UpdateChecker.cs
+++ b/Fronter.NET/Services/UpdateChecker.cs
@@ -15,7 +15,7 @@
 
 namespace Fronter.Services;
 
-public static class UpdateChecker {
+internal static class UpdateChecker {
 	private static readonly ILog Logger = LogManager.GetLogger("Update checker");
 	private static readonly HttpClient HttpClient = new() {Timeout = TimeSpan.FromMinutes(5)};
 	public static async Task<bool> IsUpdateAvailable(string commitIdFilePath, string commitIdUrl) {
@@ -149,7 +149,7 @@ private static async Task DownloadFileAsync(string installerUrl, string fileName
 		await File.WriteAllBytesAsync(fileName, responseBytes);
 	}
 
-	public static async void RunInstallerAndDie(string installerUrl, Config config, INotificationMessageManager notificationManager) {
+	public static async Task RunInstallerAndDie(string installerUrl, Config config, INotificationMessageManager notificationManager) {
 		Logger.Debug("Downloading installer...");
 
 		var fileName = Path.GetTempFileName();
diff --git a/Fronter.NET/ViewModels/MainWindowViewModel.cs b/Fronter.NET/ViewModels/MainWindowViewModel.cs
index a99a2dd4..3ad2ad8c 100644
--- a/Fronter.NET/ViewModels/MainWindowViewModel.cs
+++ b/Fronter.NET/ViewModels/MainWindowViewModel.cs
@@ -30,7 +30,7 @@
 namespace Fronter.ViewModels;
 
 [SuppressMessage("ReSharper", "MemberCanBeMadeStatic.Global")]
-public sealed class MainWindowViewModel : ViewModelBase {
+internal sealed class MainWindowViewModel : ViewModelBase {
 	private static readonly ILog logger = LogManager.GetLogger("Frontend");
 	private readonly TranslationSource loc = TranslationSource.Instance;
 	public IEnumerable<MenuItemViewModel> LanguageMenuItems => loc.LoadedLanguages
@@ -313,7 +313,7 @@ await Dispatcher.UIThread.InvokeAsync(async () => {
 
 		// If we can use an installer, download it, run it, and exit.
 		if (info.UseInstaller) {
-			UpdateChecker.RunInstallerAndDie(info.AssetUrl, Config, NotificationManager);
+			await UpdateChecker.RunInstallerAndDie(info.AssetUrl, Config, NotificationManager);
 		} else{
 			UpdateChecker.StartUpdaterAndDie(info.AssetUrl, Config.ConverterFolder);
 		}
diff --git a/Fronter.NET/ViewModels/OptionsViewModel.cs b/Fronter.NET/ViewModels/OptionsViewModel.cs
index 5247be0a..c6a0b359 100644
--- a/Fronter.NET/ViewModels/OptionsViewModel.cs
+++ b/Fronter.NET/ViewModels/OptionsViewModel.cs
@@ -4,7 +4,7 @@
 
 namespace Fronter.ViewModels;
 
-public sealed class OptionsViewModel : ViewModelBase {
+internal sealed class OptionsViewModel : ViewModelBase {
 	public OptionsViewModel(IEnumerable<Option> items) {
 		Items = new ObservableCollection<Option>(items);
 	}