diff --git a/src/elements/core.c b/src/elements/core.c
index 14d6710f..ade4f4ac 100644
--- a/src/elements/core.c
+++ b/src/elements/core.c
@@ -4109,8 +4109,9 @@ int mdbx_txn_begin(MDBX_env *env, MDBX_txn *parent, unsigned flags,
     if (txn != env->me_txn0)
       mdbx_free(txn);
   } else {
-    mdbx_assert(env, (txn->mt_flags & ~(MDBX_RDONLY | MDBX_WRITEMAP |
-                                        MDBX_SHRINK_ALLOWED)) == 0);
+    mdbx_assert(env, (txn->mt_flags &
+                      ~(MDBX_RDONLY | MDBX_WRITEMAP | MDBX_SHRINK_ALLOWED |
+                        MDBX_NOMETASYNC | MDBX_NOSYNC | MDBX_MAPASYNC)) == 0);
     txn->mt_signature = MDBX_MT_SIGNATURE;
     *ret = txn;
     mdbx_debug("begin txn %" PRIaTXN "%c %p on env %p, root page %" PRIaPGNO