diff --git a/src/features/salt.fea b/src/features/salt.fea
index 19a890e3a..1d1c6f01f 100644
--- a/src/features/salt.fea
+++ b/src/features/salt.fea
@@ -77,3 +77,5 @@ sub uni1FDA by uni1FDA.1;
 sub uni1FDB by uni1FDB.1;
 sub afii10055 by afii10055.1;
 sub Yi-cy by Yi-cy.1;
+
+sub u by upsilon;