diff --git a/Directory.Build.props b/Directory.Build.props
index 66a4d5e4..af219597 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -47,7 +47,7 @@
     <PackageValidationBaselineVersion>17.0.0</PackageValidationBaselineVersion>
     <Product>ClangSharp</Product>
     <RootNamespace>ClangSharp</RootNamespace>
-    <VersionPrefix>20.1.2.2</VersionPrefix>
+    <VersionPrefix>20.1.2.3</VersionPrefix>
     <VersionSuffix Condition="'$(PACKAGE_PUBLISH_MODE)' != 'stable'">rc1</VersionSuffix>
     <VersionSuffix Condition="'$(GITHUB_EVENT_NAME)' == 'pull_request'">pr</VersionSuffix>
   </PropertyGroup>
diff --git a/sources/ClangSharp.PInvokeGenerator/CSharp/CSharpOutputBuilder.cs b/sources/ClangSharp.PInvokeGenerator/CSharp/CSharpOutputBuilder.cs
index 7c6c232d..f6d52daa 100644
--- a/sources/ClangSharp.PInvokeGenerator/CSharp/CSharpOutputBuilder.cs
+++ b/sources/ClangSharp.PInvokeGenerator/CSharp/CSharpOutputBuilder.cs
@@ -104,6 +104,31 @@ public void WriteIndentedLine<T>(T value)
         WriteLine(value);
     }
 
+    public void WriteLabel(string name)
+    {
+        if (_currentLine.Length >= _indentationString.Length)
+        {
+            var match = true;
+
+            for (var i = 0; i < _indentationString.Length; i++)
+            {
+                if (_currentLine[_currentLine.Length - i - 1] != _indentationString[_indentationString.Length - 1 - i])
+                {
+                    match = false;
+                    break;
+                }
+            }
+
+            if (match)
+            {
+                _ = _currentLine.Remove(_currentLine.Length - _indentationString.Length, _indentationString.Length);
+            }
+        }
+
+        Write(name);
+        WriteLine(':');
+    }
+
     public void WriteLine<T>(T value)
     {
         Write(value);
diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitDecl.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitDecl.cs
index 271e6583..fcfa5c6f 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitDecl.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitDecl.cs
@@ -7,11 +7,9 @@
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text;
-using System.Text.RegularExpressions;
 using ClangSharp.Abstractions;
 using ClangSharp.CSharp;
 using static ClangSharp.Interop.CX_CastKind;
-using static ClangSharp.Interop.CX_CharacterKind;
 using static ClangSharp.Interop.CX_DeclKind;
 using static ClangSharp.Interop.CX_StmtClass;
 using static ClangSharp.Interop.CX_StorageClass;
@@ -607,7 +605,7 @@ private void VisitFunctionDecl(FunctionDecl functionDecl)
             IsCxx = cxxMethodDecl is not null,
             IsStatic = isDllImport || (cxxMethodDecl is null) || cxxMethodDecl.IsStatic,
             NeedsNewKeyword = NeedsNewKeyword(escapedName, functionDecl.Parameters),
-            IsReadOnly = (cxxMethodDecl is not null) && cxxMethodDecl.IsConst,
+            IsReadOnly = IsReadonly(cxxMethodDecl),
             IsUnsafe = IsUnsafe(functionDecl),
             IsCtxCxxRecord = cxxRecordDecl is not null,
             IsCxxRecordCtxUnsafe = cxxRecordDecl is not null && IsUnsafe(cxxRecordDecl),
@@ -2228,7 +2226,7 @@ void OutputVtblHelperMethod(CXXRecordDecl cxxRecordDecl, CXXMethodDecl cxxMethod
                 HasFnPtrCodeGen = !_config.ExcludeFnptrCodegen,
                 IsCtxCxxRecord = true,
                 IsCxxRecordCtxUnsafe = IsUnsafe(cxxRecordDecl),
-                IsReadOnly = cxxMethodDecl.IsConst,
+                IsReadOnly = IsReadonly(cxxMethodDecl),
                 IsUnsafe = true,
                 NeedsReturnFixup = needsReturnFixup,
                 ReturnType = returnTypeName,
@@ -2353,7 +2351,7 @@ void OutputVtblHelperMethod(CXXRecordDecl cxxRecordDecl, CXXMethodDecl cxxMethod
                 body.Write(escapedCXXRecordDeclName);
                 body.Write("*)Unsafe.AsPointer(");
 
-                if (cxxMethodDecl.IsConst)
+                if (IsReadonly(cxxMethodDecl))
                 {
                     if (!_config.GenerateLatestCode)
                     {
diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitStmt.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitStmt.cs
index 25ed853c..5eaf6372 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitStmt.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.VisitStmt.cs
@@ -2070,9 +2070,7 @@ private void VisitIntegerLiteral(IntegerLiteral integerLiteral)
     private void VisitLabelStmt(LabelStmt labelStmt)
     {
         var outputBuilder = StartCSharpCode();
-
-        outputBuilder.Write(labelStmt.Decl.Name);
-        outputBuilder.WriteLine(':');
+        outputBuilder.WriteLabel(labelStmt.Decl.Name);
 
         outputBuilder.WriteIndentation();
         Visit(labelStmt.SubStmt);
diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
index 147788d7..01eb5810 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGenerator.cs
@@ -1412,7 +1412,7 @@ static void GenerateTransparentStructs(PInvokeGenerator generator, Stream? strea
                 sw.Write(indentString);
                 sw.WriteLine("    {");
                 sw.Write(indentString);
-                sw.Write("            if (obj is ");
+                sw.Write("        if (obj is ");
                 sw.Write(name);
                 sw.WriteLine(" other)");
                 sw.Write(indentString);
@@ -3258,29 +3258,22 @@ private static int GetAnonymousRecordIndex(RecordDecl recordDecl, RecordDecl par
                     index++;
                 }
 
-                if (parentRecordDecl.Parent is RecordDecl grandParentRecordDecl)
+                if (parentRecordDecl.Parent is RecordDecl grandparentRecordDecl)
                 {
-                    var parentIndex = GetAnonymousRecordIndex(parentRecordDecl, grandParentRecordDecl);
+                    var parentIndex = GetAnonymousRecordIndex(parentRecordDecl, grandparentRecordDecl);
 
                     // We can't have the nested anonymous record have the same name as the parent
                     // so skip that index and just go one higher instead. This could still conflict
                     // with another anonymous record at a different level, but that is less likely
                     // and will still be unambiguous in total.
 
-                    if (parentIndex == index)
+                    if ((parentIndex == index) || ((parentIndex > 0) && (index > parentIndex)))
                     {
                         if (recordDecl.IsUnion == parentRecordDecl.IsUnion)
                         {
                             index++;
                         }
                     }
-                    else if ((parentIndex > 0) && (index > parentIndex))
-                    {
-                        if (recordDecl.IsUnion == parentRecordDecl.AnonymousRecords[parentIndex].IsUnion)
-                        {
-                            index++;
-                        }
-                    }
                 }
             }
         }
@@ -5402,6 +5395,15 @@ private bool IsPrevContextStmt<T>([MaybeNullWhen(false)] out T cursor, out objec
         }
     }
 
+    private bool IsReadonly(CXXMethodDecl? cxxMethodDecl)
+    {
+        if (cxxMethodDecl is not null)
+        {
+            return cxxMethodDecl.IsConst || HasRemapping(cxxMethodDecl, _config._withReadonlys, matchStar: true);
+        }
+        return false;
+    }
+
     private static bool IsStmtAsWritten<T>(Cursor cursor, [MaybeNullWhen(false)] out T value, bool removeParens = false)
         where T : Stmt
     {
diff --git a/sources/ClangSharp.PInvokeGenerator/PInvokeGeneratorConfiguration.cs b/sources/ClangSharp.PInvokeGenerator/PInvokeGeneratorConfiguration.cs
index be02ba35..426f85a2 100644
--- a/sources/ClangSharp.PInvokeGenerator/PInvokeGeneratorConfiguration.cs
+++ b/sources/ClangSharp.PInvokeGenerator/PInvokeGeneratorConfiguration.cs
@@ -33,6 +33,7 @@ public sealed class PInvokeGeneratorConfiguration
     private readonly HashSet<string> _nativeTypeNamesToStrip;
     private readonly HashSet<string> _withManualImports;
     private readonly HashSet<string> _traversalNames;
+    internal readonly HashSet<string> _withReadonlys;
     internal readonly HashSet<string> _withSetLastErrors;
     internal readonly HashSet<string> _withSuppressGCTransitions;
 
@@ -87,6 +88,7 @@ public PInvokeGeneratorConfiguration(string language, string languageStandard, s
         _nativeTypeNamesToStrip = new HashSet<string>(StringComparer.Ordinal);
         _withManualImports = new HashSet<string>(StringComparer.Ordinal);
         _traversalNames = new HashSet<string>(StringComparer.Ordinal);
+        _withReadonlys = new HashSet<string>(QualifiedNameComparer.Default);
         _withSetLastErrors = new HashSet<string>(QualifiedNameComparer.Default);
         _withSuppressGCTransitions = new HashSet<string>(QualifiedNameComparer.Default);
 
@@ -516,6 +518,20 @@ public IReadOnlyDictionary<string, string> WithNamespaces
         }
     }
 
+    [AllowNull]
+    public IReadOnlyCollection<string> WithReadonlys
+    {
+        get
+        {
+            return _withReadonlys;
+        }
+
+        init
+        {
+            AddRange(_withReadonlys, value);
+        }
+    }
+
     [AllowNull]
     public IReadOnlyCollection<string> WithSetLastErrors
     {
diff --git a/sources/ClangSharpPInvokeGenerator/Program.cs b/sources/ClangSharpPInvokeGenerator/Program.cs
index 04af033e..742c0290 100644
--- a/sources/ClangSharpPInvokeGenerator/Program.cs
+++ b/sources/ClangSharpPInvokeGenerator/Program.cs
@@ -54,6 +54,7 @@ internal static class Program
     private static readonly string[] s_withManualImportOptionAliases = ["--with-manual-import", "-wmi"];
     private static readonly string[] s_withNamespaceOptionAliases = ["--with-namespace", "-wn"];
     private static readonly string[] s_withPackingOptionAliases = ["--with-packing", "-wp"];
+    private static readonly string[] s_withReadonlyOptionAliases = ["--with-readonly", "-wro"];
     private static readonly string[] s_withSetLastErrorOptionAliases = ["--with-setlasterror", "-wsle"];
     private static readonly string[] s_withSuppressGCTransitionOptionAliases = ["--with-suppressgctransition", "-wsgct"];
     private static readonly string[] s_withTransparentStructOptionAliases = ["--with-transparent-struct", "-wts"];
@@ -92,6 +93,7 @@ internal static class Program
     private static readonly Option<string[]> s_withManualImports = GetWithManualImportOption();
     private static readonly Option<string[]> s_withNamespaceNameValuePairs = GetWithNamespaceOption();
     private static readonly Option<string[]> s_withPackingNameValuePairs = GetWithPackingOption();
+    private static readonly Option<string[]> s_withReadonlys = GetWithReadonlyOption();
     private static readonly Option<string[]> s_withSetLastErrors = GetWithSetLastErrorOption();
     private static readonly Option<string[]> s_withSuppressGCTransitions = GetWithSuppressGCTransitionOption();
     private static readonly Option<string[]> s_withTransparentStructNameValuePairs = GetWithTransparentStructOption();
@@ -255,6 +257,7 @@ public static void Run(InvocationContext context)
         var withLibraryPathNameValuePairs = context.ParseResult.GetValueForOption(s_withLibraryPathNameValuePairs) ?? [];
         var withManualImports = context.ParseResult.GetValueForOption(s_withManualImports) ?? [];
         var withNamespaceNameValuePairs = context.ParseResult.GetValueForOption(s_withNamespaceNameValuePairs) ?? [];
+        var withReadonlys = context.ParseResult.GetValueForOption(s_withReadonlys) ?? [];
         var withSetLastErrors = context.ParseResult.GetValueForOption(s_withSetLastErrors) ?? [];
         var withSuppressGCTransitions = context.ParseResult.GetValueForOption(s_withSuppressGCTransitions) ?? [];
         var withTransparentStructNameValuePairs = context.ParseResult.GetValueForOption(s_withTransparentStructNameValuePairs) ?? [];
@@ -729,6 +732,7 @@ public static void Run(InvocationContext context)
             WithLibraryPaths = withLibraryPaths,
             WithManualImports = withManualImports,
             WithNamespaces = withNamespaces,
+            WithReadonlys = withReadonlys,
             WithSetLastErrors = withSetLastErrors,
             WithSuppressGCTransitions = withSuppressGCTransitions,
             WithTransparentStructs = withTransparentStructs,
@@ -1202,6 +1206,7 @@ private static RootCommand GetRootCommand()
             s_withManualImports,
             s_withNamespaceNameValuePairs,
             s_withPackingNameValuePairs,
+            s_withReadonlys,
             s_withSetLastErrors,
             s_withSuppressGCTransitions,
             s_withTransparentStructNameValuePairs,
@@ -1350,6 +1355,17 @@ private static Option<string[]> GetWithNamespaceOption()
         };
     }
 
+    private static Option<string[]> GetWithReadonlyOption()
+    {
+        return new Option<string[]>(
+            aliases: s_withReadonlyOptionAliases,
+            description: "Add the readonly modifier to a given instance method. Supports wildcards.",
+            getDefaultValue: Array.Empty<string>
+        ) {
+            AllowMultipleArgumentsPerToken = true
+        };
+    }
+
     private static Option<string[]> GetWithSetLastErrorOption()
     {
         return new Option<string[]>(
diff --git a/sources/ClangSharpPInvokeGenerator/Properties/launchSettings.json b/sources/ClangSharpPInvokeGenerator/Properties/launchSettings.json
index cef15055..b961eec5 100644
--- a/sources/ClangSharpPInvokeGenerator/Properties/launchSettings.json
+++ b/sources/ClangSharpPInvokeGenerator/Properties/launchSettings.json
@@ -12,7 +12,7 @@
     "GenerateLocal": {
       "commandName": "Project",
       "commandLineArgs": "@generate.rsp",
-      "workingDirectory": "D:\\repos\\terrafx.interop.windows\\generation\\DirectX\\um\\dcommon"
+      "workingDirectory": "D:\\repos\\terrafx.interop.windows\\generation\\windows\\um\\winioctl"
     }
   }
 }