diff --git a/heed/src/mdb/lmdb_flags.rs b/heed/src/mdb/lmdb_flags.rs
index f12464ac..ec679168 100644
--- a/heed/src/mdb/lmdb_flags.rs
+++ b/heed/src/mdb/lmdb_flags.rs
@@ -16,6 +16,8 @@ bitflags! {
         const NO_SUB_DIR = ffi::MDB_NOSUBDIR;
         /// Don't fsync after commit.
         const NO_SYNC = ffi::MDB_NOSYNC;
+        /// Open the previous transaction.
+        const PREVSNAPSHOT = ffi::MDB_PREVSNAPSHOT;
         /// Read only.
         const READ_ONLY = ffi::MDB_RDONLY;
         /// Don't fsync metapage after commit.