diff --git a/src/CryptoNoteCore/BlockIndex.h b/src/CryptoNoteCore/BlockIndex.h
index 04d8b5ce..c122c315 100644
--- a/src/CryptoNoteCore/BlockIndex.h
+++ b/src/CryptoNoteCore/BlockIndex.h
@@ -5,6 +5,8 @@
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#pragma once
+
 #include <boost/multi_index_container.hpp>
 #include <boost/multi_index/hashed_index.hpp>
 #include <boost/multi_index/random_access_index.hpp>