diff --git a/src/ifcparse/IfcFile.h b/src/ifcparse/IfcFile.h
index 030321d9ee..b14cea367d 100644
--- a/src/ifcparse/IfcFile.h
+++ b/src/ifcparse/IfcFile.h
@@ -127,6 +127,10 @@ public:
         return storage_.byref_excl_;
     }
 
+    std::vector<std::unique_ptr<IfcUtil::IfcBaseClass>> steal_instances() {
+        return storage_.steal_instances();
+    }
+
     InstanceStreamer(const std::string& fn);
 
     InstanceStreamer(void* data, int length);
diff --git a/src/ifcparse/IfcParse.cpp b/src/ifcparse/IfcParse.cpp
index 183047b6fd..bbf80c3b65 100644
--- a/src/ifcparse/IfcParse.cpp
+++ b/src/ifcparse/IfcParse.cpp
@@ -725,7 +725,7 @@ void IfcParse::impl::in_memory_file_storage::load(unsigned entity_instance_name,
                     // the 2nd pass.
                     load(entity_instance_name, entity, ps, attribute_index == -1 ? (int)attribute_index_within_data : attribute_index);
                     auto* simple_type_instance = (schema ? schema : file->schema())->instantiate(decl, ps.construct(entity_instance_name, *references_to_resolve, decl, boost::none, attribute_index == -1 ? (int)attribute_index_within_data : attribute_index));
-                    read_simple_type_instances.push_back(simple_type_instance);
+                    read_simple_type_instances.emplace_back(simple_type_instance);
                     //@todo decide addEntity(((IfcUtil::IfcBaseClass*)*entity));
                     context.push(simple_type_instance);
                     simple_type_instance->file_ = file;
@@ -1651,6 +1651,9 @@ void IfcParse::impl::in_memory_file_storage::read_from_stream(IfcParse::IfcSpfSt
 
 	good_ = streamer.status();
 	byref_excl_ = streamer.inverses();
+    
+	// Move the storage of simple type instances so that they are retained during the lifetime of the file
+    read_simple_type_instances = streamer.steal_instances();
 
     Logger::Status("\rDone scanning file   ");
 
diff --git a/src/ifcparse/storage.h b/src/ifcparse/storage.h
index d0ebf4320c..db0e1f95b6 100644
--- a/src/ifcparse/storage.h
+++ b/src/ifcparse/storage.h
@@ -189,7 +189,10 @@ namespace IfcParse {
 
     namespace impl {
         struct IFC_PARSE_API in_memory_file_storage {
-            std::vector<IfcUtil::IfcBaseClass*> read_simple_type_instances;
+            std::vector<std::unique_ptr<IfcUtil::IfcBaseClass>> read_simple_type_instances;
+            std::vector<std::unique_ptr<IfcUtil::IfcBaseClass>> steal_instances() {
+                return std::move(read_simple_type_instances);
+            }
 
             IfcParse::IfcSpfLexer* tokens;
             // IfcParse::IfcSpfStream* stream;
@@ -214,14 +217,10 @@ namespace IfcParse {
             typedef entity_instance_by_name_t::iterator iterator;
 
             in_memory_file_storage(IfcParse::IfcFile* f = nullptr) : tokens(nullptr), file(f), schema(nullptr) {}
-            ~in_memory_file_storage() {
-                for (auto* inst : read_simple_type_instances) {
-                    delete inst;
-                }
-            }
             in_memory_file_storage(const in_memory_file_storage&) = delete;
             in_memory_file_storage(const in_memory_file_storage&&) = delete;
 
+
             class type_iterator : public entities_by_type_t::const_iterator {
             public:
                 using iterator_category = std::forward_iterator_tag;
diff --git a/src/serializers/RocksDbSerializer.cpp b/src/serializers/RocksDbSerializer.cpp
index 014b519807..f38170411b 100644
--- a/src/serializers/RocksDbSerializer.cpp
+++ b/src/serializers/RocksDbSerializer.cpp
@@ -259,7 +259,8 @@ void RocksDbSerializer::write_streaming_() {
 				}
 
 				// @nb we also need to delete them
-				delete inst;
+				// not anymore, as they are now registered as unique_ptr in the in_memory_file_storage
+				// delete inst;
 			}
 
 			// Entity type as numeric ref to index_in_schema