diff --git a/libraries/liblmdb/Makefile b/libraries/liblmdb/Makefile
index bca5cd3..90e4e21 100644
--- a/libraries/liblmdb/Makefile
+++ b/libraries/liblmdb/Makefile
@@ -11,6 +11,7 @@
 # - MDB_USE_POSIX_SEM
 # - MDB_DSYNC
 # - MDB_FDATASYNC
+# - MDB_SAFE_FDATASYNC
 # - MDB_USE_PWRITEV
 #
 # There may be other macros in mdb.c of interest. You should