diff --git a/Plugins/Wox.Plugin.Program/AddProgramSource.xaml.cs b/Plugins/Wox.Plugin.Program/AddProgramSource.xaml.cs
index 3e09d62b84..6027621de4 100644
--- a/Plugins/Wox.Plugin.Program/AddProgramSource.xaml.cs
+++ b/Plugins/Wox.Plugin.Program/AddProgramSource.xaml.cs
@@ -1,6 +1,6 @@
 using System.Windows;
 using System.Windows.Forms;
-using Wox.Plugin.Program.ProgramSources;
+using Wox.Plugin.Program.Programs;
 
 namespace Wox.Plugin.Program
 {
@@ -9,7 +9,7 @@ namespace Wox.Plugin.Program
     /// </summary>
     public partial class AddProgramSource
     {
-        private UnregisteredPrograms _editing;
+        private Settings.ProgramSource _editing;
         private Settings _settings;
 
         public AddProgramSource(Settings settings)
@@ -19,7 +19,7 @@ namespace Wox.Plugin.Program
             Directory.Focus();
         }
 
-        public AddProgramSource(UnregisteredPrograms edit, Settings settings)
+        public AddProgramSource(Settings.ProgramSource edit, Settings settings)
         {
             _editing = edit;
             _settings = settings;
@@ -49,7 +49,7 @@ namespace Wox.Plugin.Program
 
             if(_editing == null)
             {
-                var source = new UnregisteredPrograms
+                var source = new Settings.ProgramSource
                 {
                     Location = Directory.Text,
                     MaxDepth = max
diff --git a/Plugins/Wox.Plugin.Program/Main.cs b/Plugins/Wox.Plugin.Program/Main.cs
index d5d249e1cf..49669fa812 100644
--- a/Plugins/Wox.Plugin.Program/Main.cs
+++ b/Plugins/Wox.Plugin.Program/Main.cs
@@ -7,14 +7,14 @@ using System.Windows.Controls;
 using Wox.Infrastructure;
 using Wox.Infrastructure.Logger;
 using Wox.Infrastructure.Storage;
-using Wox.Plugin.Program.ProgramSources;
+using Wox.Plugin.Program.Programs;
 using Stopwatch = Wox.Infrastructure.Stopwatch;
 
 namespace Wox.Plugin.Program
 {
     public class Main : ISettingProvider, IPlugin, IPluginI18n, IContextMenu, ISavable
     {
-        private static List<Program> _programs = new List<Program>();
+        private static List<Win32> _programs = new List<Win32>();
         private static List<UWP> _uwps = new List<UWP>();
 
         private PluginInitContext _context;
@@ -59,12 +59,12 @@ namespace Wox.Plugin.Program
             return result;
         }
 
-        public Result ResultFromProgram(Program p)
+        public Result ResultFromProgram(Win32 p)
         {
             var result = new Result
             {
                 Title = p.Title,
-                SubTitle = p.Path,
+                SubTitle = p.ExecutablePath,
                 IcoPath = p.IcoPath,
                 Score = p.Score,
                 ContextData = p,
@@ -72,7 +72,7 @@ namespace Wox.Plugin.Program
                 {
                     var info = new ProcessStartInfo
                     {
-                        FileName = p.Path,
+                        FileName = p.ExecutablePath,
                         WorkingDirectory = p.Directory
                     };
                     var hide = StartProcess(info);
@@ -101,7 +101,7 @@ namespace Wox.Plugin.Program
         }
 
 
-        private int Score(Program program, string query)
+        private int Score(Win32 program, string query)
         {
             var score1 = StringMatcher.Score(program.Title, query);
             var score2 = StringMatcher.ScoreForPinyin(program.Title, query);
@@ -128,59 +128,27 @@ namespace Wox.Plugin.Program
 
         public static void IndexPrograms()
         {
-            var sources = ProgramSources();
-
-
-            var programs = sources.AsParallel()
-                    .SelectMany(s => s.LoadPrograms())
-                // filter duplicate program
-                .GroupBy(x => new { ExecutePath = x.Path, ExecuteName = x.ExecutableName })
-                .Select(g => g.First());
-            programs = programs.Select(ScoreFilter);
-
-            _programs = programs.ToList();
-            _cache.Programs = _programs;
-
-            var windows10 = new Version(10, 0);
-            var support = Environment.OSVersion.Version.Major >= windows10.Major;
-            if (support)
-            {
-                _uwps = UWP.All();
-            }
+            _cache.Programs = AllWin32Programs();
+            _uwps = UWP.All();
         }
 
-        private static List<ProgramSource> ProgramSources()
+        private static List<Win32> AllWin32Programs()
         {
-            var sources = new List<ProgramSource>();
-            var source1 = _settings.ProgramSources;
-            sources.AddRange(source1);
-            if (_settings.EnableStartMenuSource)
-            {
-                var source2 = new StartMenu();
-                sources.Add(source2);
-            }
-            if (_settings.EnableRegistrySource)
-            {
-                var source3 = new AppPathsPrograms();
-                sources.Add(source3);
-            }
+            var appPaths = AppPathsPrograms.All();
+            var startMenu = StartMenu.All(_settings.ProgramSuffixes);
+            var unregistered = UnregisteredPrograms.All(_settings.ProgramSources, _settings.ProgramSuffixes);
+            var programs = appPaths.Concat(startMenu).Concat(unregistered);
 
-            FileChangeWatcher.AddAll(source1, _settings.ProgramSuffixes);
-            foreach (var source in sources)
-            {
-                var win32 = source as Win32;
-                if (win32 != null)
-                {
-                    win32.Suffixes = _settings.ProgramSuffixes;
-                }
-            }
+            programs = programs.AsParallel()
+                                // filter duplicate program
+                               .GroupBy(x => new { ExecutePath = x.ExecutablePath, ExecuteName = x.ExecutableName })
+                               .Select(g => g.First())
+                               .Select(ScoreFilter);
 
-            return sources;
+            return programs.ToList();
         }
 
-        
-
-        private static Program ScoreFilter(Program p)
+        private static Win32 ScoreFilter(Win32 p)
         {
             var start = new[] { "启动", "start" };
             var doc = new[] { "帮助", "help", "文档", "documentation" };
@@ -222,7 +190,7 @@ namespace Wox.Plugin.Program
 
         public List<Result> LoadContextMenus(Result selectedResult)
         {
-            Program p = selectedResult.ContextData as Program;
+            Win32 p = selectedResult.ContextData as Win32;
             if (p != null)
             {
                 List<Result> contextMenus = new List<Result>
@@ -234,7 +202,7 @@ namespace Wox.Plugin.Program
                         {
                             var info = new ProcessStartInfo
                             {
-                                FileName = p.Path,
+                                FileName = p.ExecutablePath,
                                 WorkingDirectory = p.Directory,
                                 Verb = "runas"
                             };
diff --git a/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs b/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
index 11c0c41163..480f7d66d6 100644
--- a/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
+++ b/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
@@ -1,11 +1,12 @@
 using System;
 using System.Collections.Generic;
+using Wox.Plugin.Program.Programs;
 
 namespace Wox.Plugin.Program
 {
     [Serializable]
     public class ProgramIndexCache
     {
-        public List<Program> Programs = new List<Program>();
+        public List<Win32> Programs = new List<Win32>();
     }
 }
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/ProgramSetting.xaml.cs b/Plugins/Wox.Plugin.Program/ProgramSetting.xaml.cs
index 163d12f128..5bbb90e9a6 100644
--- a/Plugins/Wox.Plugin.Program/ProgramSetting.xaml.cs
+++ b/Plugins/Wox.Plugin.Program/ProgramSetting.xaml.cs
@@ -2,7 +2,7 @@
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
-using Wox.Plugin.Program.ProgramSources;
+using Wox.Plugin.Program.Programs;
 
 namespace Wox.Plugin.Program
 {
@@ -51,7 +51,7 @@ namespace Wox.Plugin.Program
 
         private void btnDeleteProgramSource_OnClick(object sender, RoutedEventArgs e)
         {
-            var selectedProgramSource = programSourceView.SelectedItem as UnregisteredPrograms;
+            var selectedProgramSource = programSourceView.SelectedItem as Settings.ProgramSource;
             if (selectedProgramSource != null)
             {
                 string msg = string.Format(context.API.GetTranslation("wox_plugin_program_delete_program_source"), selectedProgramSource.Location);
@@ -71,7 +71,7 @@ namespace Wox.Plugin.Program
 
         private void btnEditProgramSource_OnClick(object sender, RoutedEventArgs e)
         {
-            var selectedProgramSource = programSourceView.SelectedItem as UnregisteredPrograms;
+            var selectedProgramSource = programSourceView.SelectedItem as Settings.ProgramSource;
             if (selectedProgramSource != null)
             {
                 var add = new AddProgramSource(selectedProgramSource, _settings);
@@ -120,7 +120,7 @@ namespace Wox.Plugin.Program
                 {
                     if (Directory.Exists(s))
                     {
-                        _settings.ProgramSources.Add(new UnregisteredPrograms
+                        _settings.ProgramSources.Add(new Settings.ProgramSource
                         {
                             Location = s
                         });
diff --git a/Plugins/Wox.Plugin.Program/Programs/AppPathsPrograms.cs b/Plugins/Wox.Plugin.Program/Programs/AppPathsPrograms.cs
index 6f37847dd7..c7af623356 100644
--- a/Plugins/Wox.Plugin.Program/Programs/AppPathsPrograms.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/AppPathsPrograms.cs
@@ -4,15 +4,15 @@ using System.IO;
 using System.Linq;
 using Microsoft.Win32;
 
-namespace Wox.Plugin.Program.ProgramSources
+namespace Wox.Plugin.Program.Programs
 {
     [Serializable]
     public class AppPathsPrograms : Win32
     {
-        public override List<Program> LoadPrograms()
+        public static IEnumerable<Win32> All()
         {
             // https://msdn.microsoft.com/en-us/library/windows/desktop/ee872121
-            var programs = new List<Program>();
+            var programs = new List<Win32>();
             const string appPaths = @"SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths";
             using (var root = Registry.LocalMachine.OpenSubKey(appPaths))
             {
@@ -31,7 +31,7 @@ namespace Wox.Plugin.Program.ProgramSources
             return programs;
         }
 
-        private IEnumerable<Program> ProgramsFromRegistryKey(RegistryKey root)
+        private static IEnumerable<Win32> ProgramsFromRegistryKey(RegistryKey root)
         {
             var programs = root.GetSubKeyNames()
                                .Select(subkey => ProgramFromRegistrySubkey(root, subkey))
@@ -39,7 +39,7 @@ namespace Wox.Plugin.Program.ProgramSources
             return programs;
         }
 
-        private Program ProgramFromRegistrySubkey(RegistryKey root, string subkey)
+        private static Win32 ProgramFromRegistrySubkey(RegistryKey root, string subkey)
         {
             using (var key = root.OpenSubKey(subkey))
             {
@@ -62,7 +62,7 @@ namespace Wox.Plugin.Program.ProgramSources
                     }
                 }
             }
-            return new Program();
+            return new Win32();
         }
     }
 }
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/Programs/Program.cs b/Plugins/Wox.Plugin.Program/Programs/Program.cs
deleted file mode 100644
index 721e2ec717..0000000000
--- a/Plugins/Wox.Plugin.Program/Programs/Program.cs
+++ /dev/null
@@ -1,15 +0,0 @@
-using System;
-
-namespace Wox.Plugin.Program
-{
-    [Serializable]
-    public class Program
-    {
-        public string Title { get; set; }
-        public string IcoPath { get; set; }
-        public string Path { get; set; }
-        public string Directory { get; set; }
-        public string ExecutableName { get; set; }
-        public int Score { get; set; }
-    }
-}
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/Programs/ProgramSource.cs b/Plugins/Wox.Plugin.Program/Programs/ProgramSource.cs
deleted file mode 100644
index 2a6c6a43b8..0000000000
--- a/Plugins/Wox.Plugin.Program/Programs/ProgramSource.cs
+++ /dev/null
@@ -1,11 +0,0 @@
-using System;
-using System.Collections.Generic;
-
-namespace Wox.Plugin.Program.ProgramSources
-{
-    [Serializable]
-    public abstract class ProgramSource
-    {
-        public abstract List<Program> LoadPrograms();
-    }
-}
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/Programs/StartMenu.cs b/Plugins/Wox.Plugin.Program/Programs/StartMenu.cs
index 2ee63ac2d4..e8a364cffc 100644
--- a/Plugins/Wox.Plugin.Program/Programs/StartMenu.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/StartMenu.cs
@@ -1,18 +1,18 @@
 using System;
 using System.Collections.Generic;
 
-namespace Wox.Plugin.Program.ProgramSources
+namespace Wox.Plugin.Program.Programs
 {
     [Serializable]
     class StartMenu : Win32
     {
-        public override List<Program> LoadPrograms()
+        public static IEnumerable<Win32> All(string[] suffixes)
         {
             var directory1 = Environment.GetFolderPath(Environment.SpecialFolder.Programs);
             var directory2 = Environment.GetFolderPath(Environment.SpecialFolder.CommonPrograms);
-            var programs = new List<Program>();
-            GetAppFromDirectory(programs, directory1, MaxDepth);
-            GetAppFromDirectory(programs, directory2, MaxDepth);
+            var programs = new List<Win32>();
+            GetAppFromDirectory(programs, directory1, -1, suffixes);
+            GetAppFromDirectory(programs, directory2, -1, suffixes);
             return programs;
         }
     }
diff --git a/Plugins/Wox.Plugin.Program/Programs/UWP.cs b/Plugins/Wox.Plugin.Program/Programs/UWP.cs
index 11c9cc818e..fd7c3a52b6 100644
--- a/Plugins/Wox.Plugin.Program/Programs/UWP.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/UWP.cs
@@ -14,11 +14,12 @@ using Windows.Management.Deployment;
 using Windows.Storage.Streams;
 using AppxPackaing;
 using Shell;
+using Wox.Infrastructure;
 using Wox.Infrastructure.Logger;
 using IStream = AppxPackaing.IStream;
 using Rect = System.Windows.Rect;
 
-namespace Wox.Plugin.Program.ProgramSources
+namespace Wox.Plugin.Program.Programs
 {
     public class UWP
     {
@@ -119,26 +120,35 @@ namespace Wox.Plugin.Program.ProgramSources
 
         public static List<UWP> All()
         {
-            var packages = CurrentUserPackages();
-            var uwps = new List<UWP>();
-            Parallel.ForEach(packages, p =>
+            var windows10 = new Version(10, 0);
+            var support = Environment.OSVersion.Version.Major >= windows10.Major;
+            if (support)
             {
-                try
+                var packages = CurrentUserPackages();
+                var uwps = new List<UWP>();
+                Parallel.ForEach(packages, p =>
                 {
-                    var u = new UWP(p);
-                    if (u.Apps.Length > 0)
+                    try
                     {
-                        uwps.Add(u);
+                        var u = new UWP(p);
+                        if (u.Apps.Length > 0)
+                        {
+                            uwps.Add(u);
+                        }
                     }
-                }
-                catch (Exception e)
-                {
-                    // if there are errors, just ignore it and continue
-                    var message = $"Can't parse {p.Id.Name}: {e.Message}";
-                    Log.Error(message);
-                }
-            });
-            return uwps;
+                    catch (Exception e)
+                    {
+                        // if there are errors, just ignore it and continue
+                        var message = $"Can't parse {p.Id.Name}: {e.Message}";
+                        Log.Error(message);
+                    }
+                });
+                return uwps;
+            }
+            else
+            {
+                return new List<UWP>();
+            }
         }
 
         private static IEnumerable<Package> CurrentUserPackages()
@@ -244,8 +254,7 @@ namespace Wox.Plugin.Program.ProgramSources
                 }
                 else
                 {
-                    // todo: replaced with wox error logo
-                    return new BitmapImage();
+                    return new BitmapImage(new Uri(Constant.ErrorIcon));
                 }
             }
 
@@ -310,8 +319,7 @@ namespace Wox.Plugin.Program.ProgramSources
                 }
                 else
                 {
-                    var bitmap = new BitmapImage();
-                    return bitmap;
+                    return new BitmapImage(new Uri(Constant.ErrorIcon));
                 }
             }
 
diff --git a/Plugins/Wox.Plugin.Program/Programs/UnregisteredPrograms.cs b/Plugins/Wox.Plugin.Program/Programs/UnregisteredPrograms.cs
index 1418cea5ba..58a629d807 100644
--- a/Plugins/Wox.Plugin.Program/Programs/UnregisteredPrograms.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/UnregisteredPrograms.cs
@@ -2,25 +2,22 @@
 using System.Collections.Generic;
 using System.IO;
 
-namespace Wox.Plugin.Program.ProgramSources
+namespace Wox.Plugin.Program.Programs
 {
     [Serializable]
     public class UnregisteredPrograms : Win32
     {
-        public string Location { get; set; } = "";
-
-        public override List<Program> LoadPrograms()
+        public static List<Win32> All(List<Settings.ProgramSource> sources, string[] suffixes)
         {
-            if (Directory.Exists(Location) && MaxDepth >= -1)
+            List<Win32> programs = new List<Win32>();
+            foreach (var source in sources)
             {
-                var apps = new List<Program>();
-                GetAppFromDirectory(apps, Location, MaxDepth);
-                return apps;
-            }
-            else
-            {
-                return new List<Program>();
+                if (System.IO.Directory.Exists(source.Location) && source.MaxDepth >= -1)
+                {
+                    GetAppFromDirectory(programs, source.Location, source.MaxDepth, suffixes);
+                }
             }
+            return programs;
         }
     }
 }
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/Programs/Win32.cs b/Plugins/Wox.Plugin.Program/Programs/Win32.cs
index cbd89f7103..8533a36b0c 100644
--- a/Plugins/Wox.Plugin.Program/Programs/Win32.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/Win32.cs
@@ -6,22 +6,26 @@ using System.Linq;
 using Wox.Infrastructure.Exception;
 using Wox.Infrastructure.Logger;
 
-namespace Wox.Plugin.Program.ProgramSources
+namespace Wox.Plugin.Program.Programs
 {
     [Serializable]
-    public abstract class Win32 : ProgramSource
+    public class Win32
     {
-        public int MaxDepth { get; set; } = -1;
-        public string[] Suffixes { get; set; } = { "" };
+        public string Title { get; set; }
+        public string IcoPath { get; set; }
+        public string ExecutablePath { get; set; }
+        public string Directory { get; set; }
+        public string ExecutableName { get; set; }
+        public int Score { get; set; }
 
-        protected Program CreateEntry(string file)
+        protected static Win32 CreateEntry(string file)
         {
-            var p = new Program
+            var p = new Win32
             {
                 Title = Path.GetFileNameWithoutExtension(file),
                 IcoPath = file,
-                Path = file,
-                Directory = Directory.GetParent(file).FullName
+                ExecutablePath = file,
+                Directory = System.IO.Directory.GetParent(file).FullName
             };
 
             switch (Path.GetExtension(file).ToLower())
@@ -44,33 +48,42 @@ namespace Wox.Plugin.Program.ProgramSources
             return p;
         }
 
-        protected void GetAppFromDirectory(List<Program> apps, string directory, int depth)
+        protected static void GetAppFromDirectory(List<Win32> apps, string directory, int depth, string[] suffixes)
         {
-            if (MaxDepth == -1 || MaxDepth < depth)
+            if (depth == -1)
             {
-                foreach (var f in Directory.GetFiles(directory))
+            }
+            else if (depth > 0)
+            {
+                depth = depth - 1;
+            }
+            else
+            {
+                return;
+            }
+
+            foreach (var f in System.IO.Directory.GetFiles(directory))
+            {
+                if (suffixes.Any(o => f.EndsWith("." + o)))
                 {
-                    if (Suffixes.Any(o => f.EndsWith("." + o)))
+                    Win32 p;
+                    try
                     {
-                        Program p;
-                        try
-                        {
-                            p = CreateEntry(f);
-                        }
-                        catch (Exception e)
-                        {
-                            var woxPluginException = new WoxPluginException("Program",
-                                $"GetAppFromDirectory failed: {directory}", e);
-                            Log.Exception(woxPluginException);
-                            continue;
-                        }
-                        apps.Add(p);
+                        p = CreateEntry(f);
                     }
+                    catch (Exception e)
+                    {
+                        var woxPluginException = new WoxPluginException("Program",
+                            $"GetAppFromDirectory failed: {directory}", e);
+                        Log.Exception(woxPluginException);
+                        continue;
+                    }
+                    apps.Add(p);
                 }
-                foreach (var d in Directory.GetDirectories(directory))
-                {
-                    GetAppFromDirectory(apps, d, depth - 1);
-                }
+            }
+            foreach (var d in System.IO.Directory.GetDirectories(directory))
+            {
+                GetAppFromDirectory(apps, d, depth, suffixes);
             }
         }
     }
diff --git a/Plugins/Wox.Plugin.Program/Settings.cs b/Plugins/Wox.Plugin.Program/Settings.cs
index 6eb0754fcc..fb1dabbf32 100644
--- a/Plugins/Wox.Plugin.Program/Settings.cs
+++ b/Plugins/Wox.Plugin.Program/Settings.cs
@@ -1,11 +1,11 @@
 using System.Collections.Generic;
-using Wox.Plugin.Program.ProgramSources;
+using Wox.Plugin.Program.Programs;
 
 namespace Wox.Plugin.Program
 {
     public class Settings
     {
-        public List<UnregisteredPrograms> ProgramSources { get; set; } = new List<UnregisteredPrograms>();
+        public List<ProgramSource> ProgramSources { get; set; } = new List<ProgramSource>();
         public string[] ProgramSuffixes { get; set; } = {"bat", "appref-ms", "exe", "lnk"};
 
         public bool EnableStartMenuSource { get; set; } = true;
@@ -13,5 +13,11 @@ namespace Wox.Plugin.Program
         public bool EnableRegistrySource { get; set; } = true;
 
         internal const char SuffixSeperator = ';';
+
+        public class ProgramSource
+        {
+            public string Location { get; set; }
+            public int MaxDepth { get; set; }
+        }
     }
 }
diff --git a/Plugins/Wox.Plugin.Program/Wox.Plugin.Program.csproj b/Plugins/Wox.Plugin.Program/Wox.Plugin.Program.csproj
index 7963513395..6c7ac1f2f6 100644
--- a/Plugins/Wox.Plugin.Program/Wox.Plugin.Program.csproj
+++ b/Plugins/Wox.Plugin.Program/Wox.Plugin.Program.csproj
@@ -75,13 +75,11 @@
     <Compile Include="Programs\UWP.cs" />
     <Compile Include="Programs\Win32.cs" />
     <Compile Include="SuffixesConverter.cs" />
-    <Compile Include="Programs\Program.cs" />
     <Compile Include="ProgramIndexCache.cs" />
     <Compile Include="Main.cs" />
     <Compile Include="ProgramSetting.xaml.cs">
       <DependentUpon>ProgramSetting.xaml</DependentUpon>
     </Compile>
-    <Compile Include="Programs\ProgramSource.cs" />
     <Compile Include="Programs\AppPathsPrograms.cs" />
     <Compile Include="Programs\UnregisteredPrograms.cs" />
     <Compile Include="Settings.cs" />