diff --git a/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/CategoryCasingInfo.cs b/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/CategoryCasingInfo.cs
index dd76e88d0ebd9..e43ee61323d81 100644
--- a/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/CategoryCasingInfo.cs
+++ b/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/CategoryCasingInfo.cs
@@ -43,7 +43,8 @@ public CategoryCasingInfo(CodePoint codePoint)
break;
}
- if (Program.IncludeCasingData)
+ // For compatibility reasons we are not mapping the Turkish I's nor Latin small letter long S with invariant casing.
+ if (Program.IncludeCasingData && codePoint.Value != 0x0130 && codePoint.Value != 0x0131 && codePoint.Value != 0x017f)
{
_data.offsetToSimpleUppercase = (ushort)(codePoint.SimpleUppercaseMapping - codePoint.Value);
_data.offsetToSimpleLowercase = (ushort)(codePoint.SimpleLowercaseMapping - codePoint.Value);
diff --git a/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/Program.cs b/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/Program.cs
index 49a455467a51b..3bef2414ec61a 100644
--- a/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/Program.cs
+++ b/src/coreclr/System.Private.CoreLib/Tools/GenUnicodeProp/Program.cs
@@ -11,8 +11,8 @@ namespace GenUnicodeProp
{
internal static class Program
{
- internal static bool Verbose = false;
- internal static bool IncludeCasingData = false;
+ internal static bool Verbose;
+ internal static bool IncludeCasingData;
private const string SOURCE_NAME = "CharUnicodeInfoData.cs";
diff --git a/src/libraries/Common/tests/TestUtilities.Unicode/System/Text/Unicode/CodePoint.cs b/src/libraries/Common/tests/TestUtilities.Unicode/System/Text/Unicode/CodePoint.cs
index a77acf6eaaa2a..466cd75f99a54 100644
--- a/src/libraries/Common/tests/TestUtilities.Unicode/System/Text/Unicode/CodePoint.cs
+++ b/src/libraries/Common/tests/TestUtilities.Unicode/System/Text/Unicode/CodePoint.cs
@@ -109,7 +109,7 @@ internal CodePoint(int value, ParsedUnicodeData parsedData)
///
/// See https://www.unicode.org/reports/tr44/#PropList.txt.
///
- public CodePointFlags Flags { get; } = default; // default is "no flags"
+ public CodePointFlags Flags { get; } // default is "no flags"
///
/// The general Unicode category of this code point.
diff --git a/src/libraries/System.Globalization/tests/Invariant/InvariantMode.cs b/src/libraries/System.Globalization/tests/Invariant/InvariantMode.cs
index a2cd0baf70f8e..0a0300afc5c43 100644
--- a/src/libraries/System.Globalization/tests/Invariant/InvariantMode.cs
+++ b/src/libraries/System.Globalization/tests/Invariant/InvariantMode.cs
@@ -53,6 +53,12 @@ public static IEnumerable