diff --git a/storage/rocksdb/rdb_mutex_wrapper.h b/storage/rocksdb/rdb_mutex_wrapper.h
index 1ac73eaf9ae2dd44ffff42ee46c36b0fe71af541..e5f4cd5c0d8648ff24202c7b30b6fd4d4923757e 100644
--- a/storage/rocksdb/rdb_mutex_wrapper.h
+++ b/storage/rocksdb/rdb_mutex_wrapper.h
@@ -43,3 +43,11 @@ class Rdb_mutex : public rocksdb::TransactionDBMutex {
  public:
   Rdb_mutex();
   virtual ~Rdb_mutex() override;
+
+  /*
+    Override parent class's virtual methods of interrest.
+  */
+
+  // Attempt to acquire lock.  Return OK on success, or other Status on failure.
+  // If returned status is OK, TransactionDB will eventually call UnLock().
+  virtual rocksdb::Status Lock() override;
\ No newline at end of file