diff --git a/src/BuiltInTools/dotnet-format/Formatters/CharsetFormatter.cs b/src/BuiltInTools/dotnet-format/Formatters/CharsetFormatter.cs
index b2aa5af51847..5e8d9ee6cfad 100644
--- a/src/BuiltInTools/dotnet-format/Formatters/CharsetFormatter.cs
+++ b/src/BuiltInTools/dotnet-format/Formatters/CharsetFormatter.cs
@@ -68,7 +68,8 @@ private static byte[] GetEncodedBytes(string text, Encoding encoding)
         private static bool TryGetCharset(AnalyzerConfigOptions analyzerConfigOptions, [NotNullWhen(true)] out Encoding? encoding)
         {
             if (analyzerConfigOptions != null &&
-                analyzerConfigOptions.TryGetValue("charset", out var charsetOption))
+                analyzerConfigOptions.TryGetValue("charset", out var charsetOption) &&
+                charsetOption != "unset")
             {
                 encoding = GetCharset(charsetOption);
                 return true;