diff --git a/util/mutexlock.h b/util/mutexlock.h
index 1ff5a9e..08d709a 100644
--- a/util/mutexlock.h
+++ b/util/mutexlock.h
@@ -28,11 +28,11 @@ class SCOPED_LOCKABLE MutexLock {
   }
   ~MutexLock() UNLOCK_FUNCTION() { this->mu_->Unlock(); }
 
+  MutexLock(const MutexLock&) = delete;
+  MutexLock& operator=(const MutexLock&) = delete;
+
  private:
   port::Mutex *const mu_;
-  // No copying allowed
-  MutexLock(const MutexLock&);
-  void operator=(const MutexLock&);
 };
 
 }  // namespace leveldb