diff --git a/internal/core/src/index/Index.h b/internal/core/src/index/Index.h
index a4fadb70d1..0d1cc55ef7 100644
--- a/internal/core/src/index/Index.h
+++ b/internal/core/src/index/Index.h
@@ -24,6 +24,7 @@
 #include "common/Types.h"
 
 const std::string kMmapFilepath = "mmap_filepath";
+const std::string kEnableMmap = "enable_mmap";
 
 namespace milvus::index {
 
diff --git a/internal/core/src/index/VectorMemIndex.cpp b/internal/core/src/index/VectorMemIndex.cpp
index 93d2bb9a1e..786295c8b1 100644
--- a/internal/core/src/index/VectorMemIndex.cpp
+++ b/internal/core/src/index/VectorMemIndex.cpp
@@ -482,6 +482,7 @@ VectorMemIndex::LoadFromFile(const Config& config) {
     LOG_SEGCORE_INFO_ << "load index into Knowhere...";
     auto conf = config;
     conf.erase(kMmapFilepath);
+    conf[kEnableMmap] = true;
     auto stat = index_.DeserializeFromFile(filepath.value(), conf);
     if (stat != knowhere::Status::success) {
         PanicCodeInfo(ErrorCodeEnum::UnexpectedError,