diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 2d2486d..ae82bb2 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -3744,7 +3744,8 @@ mdb_env_write_meta(MDB_txn *txn)
 		mp->mm_dbs[0] = txn->mt_dbs[0];
 		mp->mm_dbs[1] = txn->mt_dbs[1];
 		mp->mm_last_pg = txn->mt_next_pgno - 1;
-#if !(defined(_MSC_VER) || defined(__i386__) || defined(__x86_64__))
+#if (__GNUC__ * 100 + __GNUC_MINOR__ >= 404) && /* TODO: portability */	\
+	!(defined(__i386__) || defined(__x86_64__))
 		/* LY: issue a memory barrier, if not x86. ITS#7969 */
 		__sync_synchronize();
 #endif