diff --git a/StanHeaders/inst/include/upstream b/StanHeaders/inst/include/upstream
index 3a880ada0..9203984cf 160000
--- a/StanHeaders/inst/include/upstream
+++ b/StanHeaders/inst/include/upstream
@@ -1 +1 @@
-Subproject commit 3a880ada03f37b597026b8165bc9295179f6fb2a
+Subproject commit 9203984cfabf8b5fb21b897d7ae559328c2e9420