diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 578e6b6..36b02a3 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -1095,6 +1095,10 @@ mdb_dkey(MDB_val *key, char *buf)
 	char *ptr = buf;
 	unsigned char *c = key->mv_data;
 	unsigned int i;
+
+	if (!key)
+		return "";
+
 	if (key->mv_size > MDB_MAXKEYSIZE)
 		return "MDB_MAXKEYSIZE";
 	/* may want to make this a dynamic check: if the key is mostly
@@ -4823,7 +4827,7 @@ mdb_cursor_put(MDB_cursor *mc, MDB_val *key, MDB_val *data,
 	if (F_ISSET(mc->mc_txn->mt_flags, MDB_TXN_RDONLY))
 		return EACCES;
 
-	if (key->mv_size == 0 || key->mv_size > MDB_MAXKEYSIZE)
+	if (flags != MDB_CURRENT && (key->mv_size == 0 || key->mv_size > MDB_MAXKEYSIZE))
 		return EINVAL;
 
 	if (F_ISSET(mc->mc_db->md_flags, MDB_DUPSORT) && data->mv_size > MDB_MAXKEYSIZE)