diff --git a/internal/core/src/mmap/Utils.h b/internal/core/src/mmap/Utils.h
index 2824a690d0..cf6dfd0c71 100644
--- a/internal/core/src/mmap/Utils.h
+++ b/internal/core/src/mmap/Utils.h
@@ -150,6 +150,7 @@ WriteFieldData(File& file,
             }
             case DataType::VECTOR_SPARSE_FLOAT: {
                 for (size_t i = 0; i < data->get_num_rows(); ++i) {
+                    indices.push_back(total_written);
                     auto vec =
                         static_cast<const knowhere::sparse::SparseRow<float>*>(
                             data->RawValue(i));