diff --git a/Package.swift b/Package.swift
index 7388eeff..95cb6dfe 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version: 5.9
+// swift-tools-version: 6.0
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
diff --git a/Sources/JavApi/lang/FileHandle+TextOutputStream.swift b/Sources/JavApi/lang/FileHandle+TextOutputStream.swift
index 5a1f4528..a532cce4 100644
--- a/Sources/JavApi/lang/FileHandle+TextOutputStream.swift
+++ b/Sources/JavApi/lang/FileHandle+TextOutputStream.swift
@@ -6,7 +6,7 @@
 import Foundation
 
 /// Extension for FileHandle as TextOutputStream for using in System.err
-extension FileHandle: TextOutputStream {
+extension FileHandle: @retroactive TextOutputStream {
   public func write(_ string: String) {
     let data = Data(string.utf8)
     self.write(data)