diff --git a/CMakeLists.txt b/CMakeLists.txt
index 89aeb987d3d..f7241020815 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -443,6 +443,7 @@ else()
   try_append_cxx_flags("-Wvla" TARGET warn_interface SKIP_LINK)
   try_append_cxx_flags("-Wshadow-field" TARGET warn_interface SKIP_LINK)
   try_append_cxx_flags("-Wthread-safety" TARGET warn_interface SKIP_LINK)
+  try_append_cxx_flags("-Wthread-safety-pointer" TARGET warn_interface SKIP_LINK)
   try_append_cxx_flags("-Wloop-analysis" TARGET warn_interface SKIP_LINK)
   try_append_cxx_flags("-Wredundant-decls" TARGET warn_interface SKIP_LINK)
   try_append_cxx_flags("-Wunused-member-function" TARGET warn_interface SKIP_LINK)
diff --git a/src/leveldb/util/cache.cc b/src/leveldb/util/cache.cc
index 12de306cad2..2d4433fcc68 100644
--- a/src/leveldb/util/cache.cc
+++ b/src/leveldb/util/cache.cc
@@ -171,8 +171,8 @@ class LRUCache {
  private:
   void LRU_Remove(LRUHandle* e);
   void LRU_Append(LRUHandle* list, LRUHandle* e);
-  void Ref(LRUHandle* e);
-  void Unref(LRUHandle* e);
+  void Ref(LRUHandle* e) EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void Unref(LRUHandle* e) EXCLUSIVE_LOCKS_REQUIRED(mutex_);
   bool FinishErase(LRUHandle* e) EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Initialized before use.