diff --git a/Helper/File/IconReader.cs b/Helper/File/IconReader.cs
index eaf5a4c..1cc0ea4 100644
--- a/Helper/File/IconReader.cs
+++ b/Helper/File/IconReader.cs
@@ -1,5 +1,6 @@
 using Clearcove.Logging;
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
@@ -19,8 +20,7 @@ namespace SystemTrayMenu.Helper
     /// </example>
     public class IconReader
     {
-        static Dictionary<string, Icon> dictIconCache = new Dictionary<string, Icon>();
-        static readonly object lockIconCache = new object();
+        static ConcurrentDictionary<string, Icon> dictIconCache = new ConcurrentDictionary<string, Icon>();
 
         /// <summary>
         /// Options to specify the size of icons to return.
@@ -65,7 +65,7 @@ namespace SystemTrayMenu.Helper
             {
                 bool isExtensionWitSameIcon = true;
                 List<string> extensionsWithDiffIcons = new List<string>
-                { ".exe", ".ink", ".ico", ".url" };
+                { ".exe", ".lnk", ".ico", ".url" };
                 if (extensionsWithDiffIcons.Contains(fileExtension.ToLower()))
                 {
                     isExtensionWitSameIcon = false;
@@ -75,17 +75,10 @@ namespace SystemTrayMenu.Helper
 
             if (IsExtensionWitSameIcon(extension))
             {
-                lock (lockIconCache)
+                icon = dictIconCache.GetOrAdd(extension, GetIcon);
+                Icon GetIcon(string keyExtension)
                 {
-                    if (dictIconCache.ContainsKey(extension))
-                    {
-                        icon = dictIconCache[extension];
-                    }
-                    else
-                    {
-                        icon = GetFileIcon(filePath, linkOverlay, size);
-                        dictIconCache.Add(extension, icon);
-                    }
+                    return GetFileIcon(filePath, linkOverlay, size);
                 }
             }
             else
@@ -95,6 +88,7 @@ namespace SystemTrayMenu.Helper
 
             return icon;
         }
+
         private static Icon GetFileIcon(string filePath, bool linkOverlay,
             IconSize size = IconSize.Small)
         {
diff --git a/Properties/AssemblyInfo.cs b/Properties/AssemblyInfo.cs
index 8e16864..3bab3fa 100644
--- a/Properties/AssemblyInfo.cs
+++ b/Properties/AssemblyInfo.cs
@@ -9,7 +9,7 @@ using System.Runtime.InteropServices;
 [assembly: AssemblyConfiguration("")]
 [assembly: AssemblyCompany("TAMAHO")]
 [assembly: AssemblyProduct("TAMAHO SystemTrayMenu")]
-[assembly: AssemblyCopyright("Copyright © 2019, TAMAHO SystemTrayMenu")]
+[assembly: AssemblyCopyright("Copyright © 2020, TAMAHO SystemTrayMenu")]
 [assembly: AssemblyTrademark("TAMAHO")]
 [assembly: AssemblyCulture("")]
 
@@ -31,5 +31,5 @@ using System.Runtime.InteropServices;
 // You can specify all the values or you can default the Build and Revision Numbers 
 // by using the '*' as shown below:
 // [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("0.9.2.0")]
-[assembly: AssemblyFileVersion("0.9.2.0")]
+[assembly: AssemblyVersion("0.9.2.1")]
+[assembly: AssemblyFileVersion("0.9.2.1")]