diff --unified --recursive --text package.orig/CMakeLists.txt package.new/CMakeLists.txt
--- package.orig/CMakeLists.txt	2024-03-21 07:15:29.659498422 +0900
+++ package.new/CMakeLists.txt	2024-03-21 12:23:19.544892731 +0900
@@ -1,18 +1,19 @@
 project(FcstdThumbnailer)
 
 # Set minimum required version of cmake.
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.5.0)
 
-set(QT_MIN_VERSION "5.2.0")
+set(QT_MIN_VERSION "6.6.0")
+set(CMAKE_CXX_STANDARD 17)
 
 # Locate extra-cmake-modules version 0.0.11 and make it a required package
-find_package(ECM 1.0.0 REQUIRED NO_MODULE)
+find_package(ECM 6.0.0 REQUIRED NO_MODULE)
 
 # Set value of CMAKE_MODULE_PATH variable where cmake will search for modules
 set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH} ${ECM_KDE_MODULE_DIR} ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 
-find_package(Qt5Gui REQUIRED)
-find_package(KF5 REQUIRED COMPONENTS KIO Archive)
+find_package(Qt6Gui REQUIRED)
+find_package(KF6 REQUIRED COMPONENTS KIO Archive)
 
 include(FeatureSummary)
 include(WriteBasicConfigVersionFile)
@@ -23,12 +24,12 @@
 set(FcstdThumbnailer_SRCS src/fcstdcreator.cpp)
 
 add_library(fcstdthumbnailer MODULE ${FcstdThumbnailer_SRCS})
-
-target_link_libraries(fcstdthumbnailer Qt5::Gui KF5::KIOWidgets KF5::Archive)
+target_link_libraries(fcstdthumbnailer Qt6::Gui KF6::KIOWidgets KF6::Archive)
 
 # TODO: Figure out why (on my system) the documentation suggested paths don't resolve to the proper qt5 plugin path, silently breaking the plugin.
 #       The manual TARGET specification does install in the proper location.
 #install(TARGETS fcstdthumbnailer             DESTINATION ${PLUGIN_INSTALL_DIR})
 #install(TARGETS fcstdthumbnailer             DESTINATION ${QT_PLUGIN_INSTALL_DIR})
-install(TARGETS fcstdthumbnailer             DESTINATION ${LIB_INSTALL_DIR}/qt5/plugins)
-install(FILES   src/fcstdthumbnailer.desktop DESTINATION ${SERVICES_INSTALL_DIR})
+# install(TARGETS fcstdthumbnailer             DESTINATION ${LIB_INSTALL_DIR}/qt5/plugins)
+# install(FILES   src/fcstdthumbnailer.desktop DESTINATION ${SERVICES_INSTALL_DIR})
+install(TARGETS fcstdthumbnailer DESTINATION ${KDE_INSTALL_PLUGINDIR}/kf6/thumbcreator)
diff --unified --recursive --text package.orig/src/fcstdcreator.cpp package.new/src/fcstdcreator.cpp
--- package.orig/src/fcstdcreator.cpp	2024-03-20 13:10:17.047547212 +0900
+++ package.new/src/fcstdcreator.cpp	2024-03-21 08:27:17.840502719 +0900
@@ -22,56 +22,29 @@
  */
 
 #include "fcstdcreator.h"
-
 #include <kzip.h>
-
 #include <QImage>
 #include <QPainter>
+#include <KPluginFactory>
 
-extern "C"
-{
-    Q_DECL_EXPORT ThumbCreator *new_creator() {
-        return new FcstdCreator();
-    }
-}
-
-FcstdCreator::FcstdCreator() { }
-
-FcstdCreator::~FcstdCreator() { }
+K_PLUGIN_CLASS_WITH_JSON(FcstdCreator, "fcstdthumbnailer.json")
 
-bool FcstdCreator::create(const QString &path, int w, int h, QImage &img) {
-    Q_UNUSED(w);
-    Q_UNUSED(h);
-
-    bool bRet = false;
-    KZip zip(path);
+FcstdCreator::FcstdCreator(QObject* parent, const QVariantList& args): KIO::ThumbnailCreator(parent, args) {}
+KIO::ThumbnailResult FcstdCreator::create(const KIO::ThumbnailRequest& request)
+{
+    QImage img;
+    KZip zip(request.url().toLocalFile());
     if (zip.open(QIODevice::ReadOnly)) {
         const KArchiveDirectory* dir = zip.directory();
-        const KArchiveEntry* entry = dir->entry ("thumbnails/Thumbnail.png");
-
-        if ( (entry != NULL) && (entry->isFile())) {
+        const KArchiveEntry* entry = dir->entry(tr("thumbnails/Thumbnail.png"));
+        if ((entry != nullptr) && (entry->isFile())) {
             const KArchiveFile* file = (KArchiveFile*)entry;
-            QByteArray data(file->data());
-
-            if (data.size() > 0) {
+            if (QByteArray data(file->data()); data.size() > 0)
                 img.loadFromData(data, "PNG");
-                if (!img.isNull()) {
-                    //TODO: Check if this is really needed
-                    // if (img.hasAlphaChannel()) {
-                    //     QImage i = img.convertToFormat(QImage::Format_RGB32);
-                    //     img.swap(i);
-                    // }
-                    bRet = true;
-                }
-            }
         }
     }
     zip.close();
-    return bRet;
-}
-
-ThumbCreator::Flags FcstdCreator::flags() const {
-    // FreeCAD already overlays a logo (TODO: file bug report about that)
-    // return (Flags)(DrawFrame | BlendIcon);
-    return None;
+    if (!img.isNull()) return KIO::ThumbnailResult::pass(img);
+    return KIO::ThumbnailResult::fail();
 }
+#include "fcstdcreator.moc"
diff --unified --recursive --text package.orig/src/fcstdcreator.h package.new/src/fcstdcreator.h
--- package.orig/src/fcstdcreator.h	2024-03-20 13:10:17.047547212 +0900
+++ package.new/src/fcstdcreator.h	2024-03-21 08:26:59.336563552 +0900
@@ -25,16 +25,13 @@
 #define _FCSTD_CREATOR_H_
 
 #include <QObject>
-#include <kio/thumbcreator.h>
+#include <KIO/ThumbnailCreator>
 
-class FcstdCreator : public QObject, public ThumbCreator
-{
+class FcstdCreator : public KIO::ThumbnailCreator {
     Q_OBJECT
 public:
-    FcstdCreator();
-    virtual ~FcstdCreator();
-    virtual bool create(const QString &path, int w, int h, QImage &thumb);
-    virtual Flags flags() const;
+    FcstdCreator(QObject* parent, const QVariantList& args);
+    KIO::ThumbnailResult create(const KIO::ThumbnailRequest& request) override;
 };
 
 #endif // _FCSTD_CREATOR_H_