diff --git a/launcher/CMakeLists.txt b/launcher/CMakeLists.txt
index fce3bb177..e5d69986c 100644
--- a/launcher/CMakeLists.txt
+++ b/launcher/CMakeLists.txt
@@ -346,6 +346,7 @@ set(MINECRAFT_SOURCES
     minecraft/mod/TexturePackFolderModel.h
     minecraft/mod/TexturePackFolderModel.cpp
     minecraft/mod/ShaderPackFolderModel.h
+    minecraft/mod/ShaderPackFolderModel.cpp
     minecraft/mod/tasks/ResourceFolderLoadTask.h
     minecraft/mod/tasks/ResourceFolderLoadTask.cpp
     minecraft/mod/tasks/LocalModParseTask.h
diff --git a/launcher/minecraft/mod/ResourceFolderModel.cpp b/launcher/minecraft/mod/ResourceFolderModel.cpp
index 4083a7088..b6f84adab 100644
--- a/launcher/minecraft/mod/ResourceFolderModel.cpp
+++ b/launcher/minecraft/mod/ResourceFolderModel.cpp
@@ -23,6 +23,7 @@
 #include "modplatform/flame/FlameAPI.h"
 #include "modplatform/flame/FlameModIndex.h"
 #include "settings/Setting.h"
+#include "tasks/SequentialTask.h"
 #include "tasks/Task.h"
 #include "ui/dialogs/CustomMessageBox.h"
 
@@ -334,7 +335,17 @@ bool ResourceFolderModel::update()
         },
         Qt::ConnectionType::QueuedConnection);
 
-    QThreadPool::globalInstance()->start(m_current_update_task.get());
+    auto task = new SequentialTask("ResourceFolderModel::update");
+
+    Task::Ptr preUpdate(createPreUpdateTask());
+    if (preUpdate != nullptr)
+        task->addTask(preUpdate);
+
+    task->addTask(m_current_update_task);
+
+    connect(task, &Task::finished, [task] { task->deleteLater(); });
+
+    QThreadPool::globalInstance()->start(task);
 
     return true;
 }
diff --git a/launcher/minecraft/mod/ResourceFolderModel.h b/launcher/minecraft/mod/ResourceFolderModel.h
index 5c41fc520..0526b5bbf 100644
--- a/launcher/minecraft/mod/ResourceFolderModel.h
+++ b/launcher/minecraft/mod/ResourceFolderModel.h
@@ -84,7 +84,7 @@ class ResourceFolderModel : public QAbstractListModel {
     virtual bool startWatching() { return startWatching({ indexDir().absolutePath(), m_dir.absolutePath() }); }
     virtual bool stopWatching() { return stopWatching({ indexDir().absolutePath(), m_dir.absolutePath() }); }
 
-    QDir indexDir() { return { QString("%1/.index").arg(dir().absolutePath()) }; }
+    virtual QDir indexDir() const { return { QString("%1/.index").arg(dir().absolutePath()) }; }
 
     /** Given a path in the system, install that resource, moving it to its place in the
      *  instance file hierarchy.
@@ -188,6 +188,7 @@ class ResourceFolderModel : public QAbstractListModel {
     void parseFinished();
 
    protected:
+    [[nodiscard]] virtual Task* createPreUpdateTask() { return nullptr; }
     /** This creates a new update task to be executed by update().
      *
      *  The task should load and parse all resources necessary, and provide a way of accessing such results.
diff --git a/launcher/minecraft/mod/ShaderPackFolderModel.cpp b/launcher/minecraft/mod/ShaderPackFolderModel.cpp
new file mode 100644
index 000000000..ee236512d
--- /dev/null
+++ b/launcher/minecraft/mod/ShaderPackFolderModel.cpp
@@ -0,0 +1,56 @@
+#include "ShaderPackFolderModel.h"
+
+namespace {
+class ShaderPackIndexMigrateTask : public Task {
+    Q_OBJECT
+   public:
+    ShaderPackIndexMigrateTask(QDir resourceDir, QDir indexDir) : m_resourceDir(std::move(resourceDir)), m_indexDir(std::move(indexDir)) {}
+
+    void executeTask() override
+    {
+        if (!m_indexDir.exists()) {
+            qDebug() << m_indexDir.absolutePath() << "does not exist; nothing to migrate";
+            emitSucceeded();
+            return;
+        }
+
+        QStringList pwFiles = m_indexDir.entryList({ "*.pw.toml" }, QDir::Files);
+        bool movedAll = true;
+
+        for (const auto& file : pwFiles) {
+            QString src = m_indexDir.filePath(file);
+            QString dest = m_resourceDir.filePath(file);
+
+            if (QFile::rename(src, dest)) {
+                qDebug() << "Moved" << src << "to" << dest;
+            } else {
+                movedAll = false;
+                qDebug() << "Error moving" << src << "to" << dest;
+            }
+        }
+
+        if (!movedAll) {
+            // FIXME: not shown in the UI
+            emitFailed(tr("Failed to migrate everything from .index"));
+            return;
+        }
+
+        if (!m_indexDir.removeRecursively()) {
+            emitFailed(tr("Failed to remove old .index dir"));
+            return;
+        }
+
+        emitSucceeded();
+    }
+
+   private:
+    QDir m_resourceDir, m_indexDir;
+};
+}  // namespace
+
+Task* ShaderPackFolderModel::createPreUpdateTask()
+{
+    return new ShaderPackIndexMigrateTask(m_dir, ResourceFolderModel::indexDir());
+}
+
+#include "ShaderPackFolderModel.moc"
diff --git a/launcher/minecraft/mod/ShaderPackFolderModel.h b/launcher/minecraft/mod/ShaderPackFolderModel.h
index cd01f6226..9b0180180 100644
--- a/launcher/minecraft/mod/ShaderPackFolderModel.h
+++ b/launcher/minecraft/mod/ShaderPackFolderModel.h
@@ -21,5 +21,16 @@ class ShaderPackFolderModel : public ResourceFolderModel {
         return new LocalShaderPackParseTask(m_next_resolution_ticket, static_cast<ShaderPack&>(resource));
     }
 
+    QDir indexDir() const override { return m_dir; }
+
+    Task* createPreUpdateTask() override;
+
+    // avoid watching twice
+    virtual bool startWatching() override { return ResourceFolderModel::startWatching({ m_dir.absolutePath() }); }
+    virtual bool stopWatching() override { return ResourceFolderModel::stopWatching({ m_dir.absolutePath() }); }
+
     RESOURCE_HELPERS(ShaderPack);
+
+   private:
+    QMutex m_migrateLock;
 };