diff --git a/src/blockstore/blockstore_internal.h b/src/blockstore/blockstore_internal.h
index 0694587d..2998ee2c 100644
--- a/src/blockstore/blockstore_internal.h
+++ b/src/blockstore/blockstore_internal.h
@@ -1,3 +1,6 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
 #pragma once
 
 #define BS_SUBMIT_CHECK_SQES(n) \
@@ -52,3 +55,7 @@
 #ifndef RWF_ATOMIC
 #define RWF_ATOMIC 0x40
 #endif
+
+#ifndef RWF_DSYNC
+#define RWF_DSYNC 0x02
+#endif
diff --git a/src/blockstore/v1/internal.h b/src/blockstore/v1/internal.h
index f28046e4..daaefa1b 100644
--- a/src/blockstore/v1/internal.h
+++ b/src/blockstore/v1/internal.h
@@ -1,3 +1,6 @@
+// Copyright (c) Vitaliy Filippov, 2019+
+// License: VNPL-1.1 (see README.md for details)
+
 #pragma once
 
 // States are not stored on disk. Instead, they're deduced from the journal