diff --git a/internal/core/src/index/InvertedIndexTantivy.cpp b/internal/core/src/index/InvertedIndexTantivy.cpp
index 0072c3de5d0c8..0330b23817fc9 100644
--- a/internal/core/src/index/InvertedIndexTantivy.cpp
+++ b/internal/core/src/index/InvertedIndexTantivy.cpp
@@ -124,8 +124,10 @@ InvertedIndexTantivy<T>::Serialize(const Config& config) {
         new uint8_t[index_valid_data_length]);
     memcpy(index_valid_data.get(), null_offset.data(), index_valid_data_length);
     BinarySet res_set;
-    res_set.Append(
-        "index_null_offset", index_valid_data, index_valid_data_length);
+    if (index_valid_data_length > 0) {
+        res_set.Append(
+            "index_null_offset", index_valid_data, index_valid_data_length);
+    }
     milvus::Disassemble(res_set);
     return res_set;
 }