diff --git a/Plugins/Wox.Plugin.Program/Main.cs b/Plugins/Wox.Plugin.Program/Main.cs
index bb9ead2c2e..876f571bc8 100644
--- a/Plugins/Wox.Plugin.Program/Main.cs
+++ b/Plugins/Wox.Plugin.Program/Main.cs
@@ -15,6 +15,7 @@ namespace Wox.Plugin.Program
 {
     public class Main : ISettingProvider, IPlugin, IPluginI18n, IContextMenu, ISavable
     {
+        private static readonly object IndexLock = new object();
         private static Win32[] _win32s = { };
         private static UWP.Application[] _uwps = { };
 
@@ -34,25 +35,38 @@ namespace Wox.Plugin.Program
             {
                 _cacheStorage = new BinaryStorage<ProgramIndexCache>();
                 _cache = _cacheStorage.Load();
-                _win32s = _cache.Programs;
+
+                var w = _cache.Win32s;
+                _win32s = w ?? new Win32[] {};
+                var u = _cache.UWPs;
+                _uwps = u ?? new UWP.Application[] { };
+
+            });
+            Log.Info($"Preload {_win32s.Length} win32 programs from cache");
+            Log.Info($"Preload {_uwps.Length} uwps from cache");
+            Task.Run(() =>
+            {
+                Stopwatch.Normal("Program Index", IndexPrograms);
             });
-            Log.Info($"Preload {_win32s.Length} programs from cache");
-            Stopwatch.Normal("Program Index", IndexPrograms);
         }
 
         public void Save()
         {
             _settingsStorage.Save();
-            _cache.Programs = _win32s;
+            _cache.Win32s = _win32s;
+            _cache.UWPs = _uwps;
             _cacheStorage.Save();
         }
 
         public List<Result> Query(Query query)
         {
-            var results1 = _win32s.AsParallel().Select(p => p.Result(query.Search, _context.API));
-            var results2 = _uwps.AsParallel().Select(p => p.Result(query.Search, _context.API));
-            var result = results1.Concat(results2).Where(r => r.Score > 0).ToList();
-            return result;
+            lock (IndexLock)
+            {
+                var results1 = _win32s.AsParallel().Select(p => p.Result(query.Search, _context.API));
+                var results2 = _uwps.AsParallel().Select(p => p.Result(query.Search, _context.API));
+                var result = results1.Concat(results2).Where(r => r.Score > 0).ToList();
+                return result;
+            }
         }
 
         public void Init(PluginInitContext context)
@@ -62,20 +76,22 @@ namespace Wox.Plugin.Program
 
         public static void IndexPrograms()
         {
+            Win32[] w = {} ;
+            UWP.Application[] u = {};
             var t1 = Task.Run(() =>
             {
-                _win32s = Win32.All(_settings);
+                w = Win32.All(_settings);
             });
             var t2 = Task.Run(() =>
             {
-                _uwps = UWP.All();
+                u = UWP.All();
             });
             Task.WaitAll(t1, t2);
 
-            var characters = _win32s.Select(p => p.Name)
-                .Concat(_win32s.Select(p => p.Description))
-                .Concat(_uwps.Select(p => p.DisplayName))
-                .Concat(_uwps.Select(p => p.Description));
+            var characters = w.Select(p => p.Name)
+                .Concat(w.Select(p => p.Description))
+                .Concat(u.Select(p => p.DisplayName))
+                .Concat(u.Select(p => p.Description));
 
             Parallel.ForEach(characters, c =>
             {
@@ -84,6 +100,12 @@ namespace Wox.Plugin.Program
                     Alphabet.PinyinComination(c);
                 }
             });
+
+            lock (IndexLock)
+            {
+                _win32s = w;
+                _uwps = u;
+            }
         }
 
         public Control CreateSettingPanel()
diff --git a/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs b/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
index 7e63327e7a..b1c7783c2d 100644
--- a/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
+++ b/Plugins/Wox.Plugin.Program/ProgramIndexCache.cs
@@ -7,6 +7,7 @@ namespace Wox.Plugin.Program
     [Serializable]
     public class ProgramIndexCache
     {
-        public Win32[] Programs = { };
+        public Win32[] Win32s = { };
+        public UWP.Application[] UWPs = { };
     }
 }
\ No newline at end of file
diff --git a/Plugins/Wox.Plugin.Program/Programs/UWP.cs b/Plugins/Wox.Plugin.Program/Programs/UWP.cs
index b6671f9a33..edca764e11 100644
--- a/Plugins/Wox.Plugin.Program/Programs/UWP.cs
+++ b/Plugins/Wox.Plugin.Program/Programs/UWP.cs
@@ -21,6 +21,7 @@ using Rect = System.Windows.Rect;
 
 namespace Wox.Plugin.Program.Programs
 {
+    [Serializable]
     public class UWP
     {
         public string Name { get; }
@@ -29,17 +30,16 @@ namespace Wox.Plugin.Program.Programs
         public string Location { get; set; }
 
         public Application[] Apps { get; set; }
-        public Package Package { get; }
 
         public PackageVersion Version { get; set; }
 
         public UWP(Package package)
         {
-            Package = package;
-            Location = Package.InstalledLocation.Path;
-            Name = Package.Id.Name;
-            FullName = Package.Id.FullName;
-            FamilyName = Package.Id.FamilyName;
+            
+            Location = package.InstalledLocation.Path;
+            Name = package.Id.Name;
+            FullName = package.Id.FullName;
+            FamilyName = package.Id.FamilyName;
             InitializeAppInfo();
             Apps = Apps.Where(a =>
             {
@@ -143,8 +143,6 @@ namespace Wox.Plugin.Program.Programs
 
         public static Application[] All()
         {
-
-
             var windows10 = new Version(10, 0);
             var support = Environment.OSVersion.Version.Major >= windows10.Major;
             if (support)
@@ -211,7 +209,7 @@ namespace Wox.Plugin.Program.Programs
             return FamilyName.GetHashCode();
         }
 
-
+        [Serializable]
         public class Application : IProgram
         {
             public string AppListEntry { get; set; }