diff --git a/src/Storages/MergeTree/IMergeTreeDataPart.cpp b/src/Storages/MergeTree/IMergeTreeDataPart.cpp
index 2826c3e23f15..11ede661f789 100644
--- a/src/Storages/MergeTree/IMergeTreeDataPart.cpp
+++ b/src/Storages/MergeTree/IMergeTreeDataPart.cpp
@@ -347,7 +347,7 @@ const IMergeTreeDataPart::Index & IMergeTreeDataPart::getIndex() const
 {
     std::scoped_lock lock(index_mutex);
     if (!index_loaded)
-        loadIndex(lock);
+        loadIndex();
     index_loaded = true;
     return index;
 }
@@ -569,6 +569,7 @@ void IMergeTreeDataPart::removeIfNeeded()
 
 UInt64 IMergeTreeDataPart::getIndexSizeInBytes() const
 {
+    std::scoped_lock lock(index_mutex);
     UInt64 res = 0;
     for (const ColumnPtr & column : index)
         res += column->byteSize();
@@ -577,6 +578,7 @@ UInt64 IMergeTreeDataPart::getIndexSizeInBytes() const
 
 UInt64 IMergeTreeDataPart::getIndexSizeInAllocatedBytes() const
 {
+    std::scoped_lock lock(index_mutex);
     UInt64 res = 0;
     for (const ColumnPtr & column : index)
         res += column->allocatedBytes();
@@ -828,7 +830,7 @@ void IMergeTreeDataPart::appendFilesOfIndexGranularity(Strings & /* files */) co
 {
 }
 
-void IMergeTreeDataPart::loadIndex(std::scoped_lock<std::mutex> &) const
+void IMergeTreeDataPart::loadIndex() const
 {
     /// Memory for index must not be accounted as memory usage for query, because it belongs to a table.
     MemoryTrackerBlockerInThread temporarily_disable_memory_tracker;
diff --git a/src/Storages/MergeTree/IMergeTreeDataPart.h b/src/Storages/MergeTree/IMergeTreeDataPart.h
index c9dea1afcc5f..0d7acfab8919 100644
--- a/src/Storages/MergeTree/IMergeTreeDataPart.h
+++ b/src/Storages/MergeTree/IMergeTreeDataPart.h
@@ -3,6 +3,7 @@
 #include <IO/WriteSettings.h>
 #include <Core/Block.h>
 #include <base/types.h>
+#include <base/defines.h>
 #include <Core/NamesAndTypes.h>
 #include <Storages/IStorage.h>
 #include <Storages/LightweightDeleteDescription.h>
@@ -565,8 +566,8 @@ class IMergeTreeDataPart : public std::enable_shared_from_this<IMergeTreeDataPar
     /// Lazily loaded in RAM. Contains each index_granularity-th value of primary key tuple.
     /// Note that marks (also correspond to primary key) are not always in RAM, but cached. See MarkCache.h.
     mutable std::mutex index_mutex;
-    mutable Index index;
-    mutable bool index_loaded = false;
+    mutable Index index TSA_GUARDED_BY(index_mutex);
+    mutable bool index_loaded TSA_GUARDED_BY(index_mutex) = false;
 
     /// Total size of all columns, calculated once in calcuateColumnSizesOnDisk
     ColumnSize total_columns_size;
@@ -664,7 +665,7 @@ class IMergeTreeDataPart : public std::enable_shared_from_this<IMergeTreeDataPar
     virtual void appendFilesOfIndexGranularity(Strings & files) const;
 
     /// Loads the index file.
-    void loadIndex(std::scoped_lock<std::mutex> &) const;
+    void loadIndex() const TSA_REQUIRES(index_mutex);
 
     void appendFilesOfIndex(Strings & files) const;