diff --git a/mdb.c b/mdb.c
index cee98c96..c2eb13be 100644
--- a/mdb.c
+++ b/mdb.c
@@ -2862,10 +2862,10 @@ mdb_txn_renew(MDB_txn *txn)
 {
 	int rc;
 
-	if (!txn || txn->mt_dbxs)	/* A reset txn has mt_dbxs==NULL */
+	if (unlikely(!txn || !F_ISSET(txn->mt_flags, MDB_TXN_RDONLY|MDB_TXN_FINISHED)))
 		return EINVAL;
 
-	if (txn->mt_env->me_flags & MDB_FATAL_ERROR) {
+	if (unlikely(txn->mt_env->me_flags & MDB_FATAL_ERROR)) {
 		mdb_debug("environment had fatal error, must shutdown!");
 		return MDB_PANIC;
 	}
@@ -2919,6 +2919,7 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned flags, MDB_txn **ret)
 		mdb_debug("calloc: %s", strerror(errno));
 		return ENOMEM;
 	}
+	txn->mt_dbxs = env->me_dbxs;	/* static */
 	txn->mt_dbs = (MDB_db *) ((char *)txn + tsize);
 	txn->mt_dbflags = (unsigned char *)txn + size - env->me_maxdbs;
 	txn->mt_flags = flags;
@@ -2945,7 +2946,6 @@ mdb_txn_begin(MDB_env *env, MDB_txn *parent, unsigned flags, MDB_txn **ret)
 		parent->mt_child = txn;
 		txn->mt_parent = parent;
 		txn->mt_numdbs = parent->mt_numdbs;
-		txn->mt_dbxs = parent->mt_dbxs;
 		memcpy(txn->mt_dbs, parent->mt_dbs, txn->mt_numdbs * sizeof(MDB_db));
 		/* Copy parent's mt_dbflags, but clear DB_NEW */
 		for (i=0; i<txn->mt_numdbs; i++)
@@ -3082,7 +3082,7 @@ mdb_txn_end(MDB_txn *txn, unsigned mode)
 		mdb_coherent_barrier();
 		txn->mt_numdbs = 0;		/* prevent further DBI activity */
 		txn->mt_flags |= MDB_TXN_FINISHED;
-		txn->mt_dbxs = NULL;	/* mark txn as reset */
+
 	} else if (!F_ISSET(txn->mt_flags, MDB_TXN_FINISHED)) {
 		pgno_t *pghead = env->me_pghead;