diff --git a/src/dbzero/bindings/python/PyToolkit.cpp b/src/dbzero/bindings/python/PyToolkit.cpp
index d40fddc1..373a3912 100644
--- a/src/dbzero/bindings/python/PyToolkit.cpp
+++ b/src/dbzero/bindings/python/PyToolkit.cpp
@@ -292,15 +292,25 @@ namespace db0::python
             return object_ptr;
         }
         
-        auto index_object = Py_OWN(IndexDefaultObject_new());
+        auto py_index = Py_OWN(IndexDefaultObject_new());
         // retrieve actual dbzero instance
-        index_object->unload(fixture, address, access_mode);
+        py_index->unload(fixture, address, access_mode);
 
         // add list object to cache
-        if (!index_object->ext().isNoCache()) {
-            lang_cache.add(address, index_object.get());
-        }
-        return shared_py_cast<PyObject*>(std::move(index_object));
+        // NOTE: in case of Index (which requires a flush on update) we need to cache instance
+        // even if accessed as no-cache to prevent premature deletion        
+        lang_cache.add(address, py_index.get());
+
+        auto py_index_ptr = py_index.get();
+        py_index->ext().setDirtyCallback([py_index_ptr](bool incRef) {
+            if (incRef) {
+                Py_INCREF(py_index_ptr);
+            } else {
+                Py_DECREF(py_index_ptr);
+            }
+        });
+        
+        return shared_py_cast<PyObject*>(std::move(py_index));
     }
     
     PyToolkit::ObjectSharedPtr PyToolkit::unloadSet(db0::swine_ptr<Fixture> fixture, 
diff --git a/src/dbzero/object_model/index/Index.cpp b/src/dbzero/object_model/index/Index.cpp
index 7c4a3c4f..2dd16bbd 100644
--- a/src/dbzero/object_model/index/Index.cpp
+++ b/src/dbzero/object_model/index/Index.cpp
@@ -553,18 +553,6 @@ namespace db0::object_model
         super_t::moveTo(fixture);
     }
     
-    void Index::operator=(Index &&other)
-    {
-        other._flush();
-        super_t::operator=(std::move(other));
-        m_index = std::move(other.m_index);
-        m_mutation_log = std::move(other.m_mutation_log);
-        other.m_index = nullptr;
-        assert(!other.hasInstance());
-        // if m_index exists then also must have a range tree
-        assert(!m_index || hasRangeTree());
-    }
-    
     void Index::commit() const
     {
         // if m_index exists then also must have a range tree
diff --git a/src/dbzero/object_model/index/Index.hpp b/src/dbzero/object_model/index/Index.hpp
index b6aa8c64..5fbc09e8 100644
--- a/src/dbzero/object_model/index/Index.hpp
+++ b/src/dbzero/object_model/index/Index.hpp
@@ -83,7 +83,7 @@ namespace db0::object_model
         // Callback invoked when the index is marked dirty (or clean)
         // for proper lifecycle management (incRef prevents premature deletion e.g. from LangCache)
         // @param incRef true to increase ref count, false to decrease        
-        void setDirtyCallback(std::function<void(bool incRef)> &&callback) {
+        void setDirtyCallback(std::function<void(bool incRef)> &&callback) const {
             m_dirty_callback = std::move(callback);
         }
 
@@ -93,7 +93,7 @@ namespace db0::object_model
         friend struct Builder;
         void flush(bool revert);
         static void flushOp(void *, bool revert);
-        std::function<void(bool incRef)> m_dirty_callback;
+        mutable std::function<void(bool incRef)> m_dirty_callback;
         
         // Set or reset dirty state
         void setDirty(bool dirty);
@@ -186,10 +186,9 @@ namespace db0::object_model
     private: 
         // actual index instance (must be cast to a specific type)
         mutable std::shared_ptr<void> m_index;
-
-        Index(tag_no_gc, db0::swine_ptr<Fixture> &, const Index &);
         
-        void operator=(Index &&);
+        // Constructor required by moveTo (auto-hardening)
+        Index(tag_no_gc, db0::swine_ptr<Fixture> &, const Index &);
         
         bool hasRangeTree() const {
             return (*this)->m_index_addr.isValid();