diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 692feaa..67a739a 100644
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -4010,13 +4010,18 @@ mdb_env_map(MDB_env *env, void *addr)
 	if (rc)
 		return rc;
 #else
+	int mmap_flags = MAP_SHARED:
 	int prot = PROT_READ;
+#ifdef MAP_NOSYNC	/* Used on FreeBSD */
+	if (flags & MDB_NOSYNC)
+		mmap_flags |= MAP_NOSYNC;
+#endif
 	if (flags & MDB_WRITEMAP) {
 		prot |= PROT_WRITE;
 		if (ftruncate(env->me_fd, env->me_mapsize) < 0)
 			return ErrCode();
 	}
-	env->me_map = mmap(addr, env->me_mapsize, prot, MAP_SHARED,
+	env->me_map = mmap(addr, env->me_mapsize, prot, mmap_flags,
 		env->me_fd, 0);
 	if (env->me_map == MAP_FAILED) {
 		env->me_map = NULL;