diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index f330907..796ea5a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -49,6 +49,7 @@ jobs:
         uses: codecov/codecov-action@v4.0.1
         with:
           files: '**/TestResults/*/*.cobertura.xml'
+          token: ${{ secrets.CODECOV_TOKEN }}
 
   build:
     needs: [test]
diff --git a/MimeUtility.cs b/MimeUtility.cs
index e992bed..2da12ba 100644
--- a/MimeUtility.cs
+++ b/MimeUtility.cs
@@ -16,11 +16,11 @@ public static class MimeUtility
         /// </summary>
         public const string UnknownMimeType = "application/octet-stream";
 
-        static Lazy<ReadOnlyDictionary<string, string>> _lazyDictExtensions = new Lazy<ReadOnlyDictionary<string, string>>(
+        private static readonly Lazy<ReadOnlyDictionary<string, string>> _lazyDictExtensions = new Lazy<ReadOnlyDictionary<string, string>>(
             () => new ReadOnlyDictionary<string, string>(KnownMimeTypes.ALL_EXTS.Value.ToDictionary(e => e, e => KnownMimeTypes.LookupType(e)))
         );
 
-        static Lazy<ReadOnlyDictionary<string, string[]>> _lazyDictMimeTypes = new Lazy<ReadOnlyDictionary<string, string[]>>(
+        private static readonly Lazy<ReadOnlyDictionary<string, string[]>> _lazyDictMimeTypes = new Lazy<ReadOnlyDictionary<string, string[]>>(
             () => new ReadOnlyDictionary<string, string[]>(KnownMimeTypes.ALL_MIMETYPES.Value.Distinct().ToDictionary(e => e, e => KnownMimeTypes.LookupMimeType(e)))
         );
 
diff --git a/Test/Test.csproj b/Test/Test.csproj
index e613221..88906f7 100644
--- a/Test/Test.csproj
+++ b/Test/Test.csproj
@@ -8,8 +8,8 @@
   
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
-    <PackageReference Include="MSTest.TestAdapter" Version="3.2.0" />
-    <PackageReference Include="MSTest.TestFramework" Version="3.2.0" />
+    <PackageReference Include="MSTest.TestAdapter" Version="3.2.1" />
+    <PackageReference Include="MSTest.TestFramework" Version="3.2.1" />
     <PackageReference Include="Newtonsoft.Json" Version="13.0.3" />
     <PackageReference Include="System.Net.Http" Version="4.3.4" />
   </ItemGroup>