diff --git a/core-writer/src/writer/BufferedWriter.cpp b/core-writer/src/writer/BufferedWriter.cpp
index 73f8ae9..e225d3d 100644
--- a/core-writer/src/writer/BufferedWriter.cpp
+++ b/core-writer/src/writer/BufferedWriter.cpp
@@ -48,29 +48,27 @@ void BufferedWriter::write_metadata_to_file()
 {
     auto header_values_type = metadata_buffer.get_header_values_type();
 
-    if (header_values_type) {
-        for (const auto& header_type : *header_values_type) {
-            auto& dataset_name = header_type.first;
-            auto& header_data_type = header_type.second;
+    for (const auto& header_type : header_values_type) {
+        auto& dataset_name = header_type.first;
+        auto& header_data_type = header_type.second;
 
-            vector<size_t> data_shape = {header_data_type.value_shape};
+        vector<size_t> data_shape = {header_data_type.value_shape};
 
-            create_dataset(
-                    dataset_name,
-                    data_shape,
-                    header_data_type.type,
-                    header_data_type.endianness,
-                    false,
-                    metadata_buffer.get_n_images());
+        create_dataset(
+                dataset_name,
+                data_shape,
+                header_data_type.type,
+                header_data_type.endianness,
+                false,
+                metadata_buffer.get_n_slots());
 
-            H5::AtomType dataset_data_type(
-                    H5FormatUtils::get_dataset_data_type(header_data_type.type));
-            dataset_data_type.setOrder(H5T_ORDER_LE);
+        H5::AtomType dataset_data_type(
+                H5FormatUtils::get_dataset_data_type(header_data_type.type));
+        dataset_data_type.setOrder(H5T_ORDER_LE);
 
-            auto& dataset = datasets.at(dataset_name);
-            dataset.write(
-                    metadata_buffer.get_metadata_values(dataset_name).get(),
-                    dataset_data_type);
-        }
+        auto& dataset = datasets.at(dataset_name);
+        dataset.write(
+                metadata_buffer.get_metadata_values(dataset_name).get(),
+                dataset_data_type);
     }
 }
\ No newline at end of file