diff --git a/StanHeaders/inst/include/upstream b/StanHeaders/inst/include/upstream
index 4a0c0e882..21cef932e 160000
--- a/StanHeaders/inst/include/upstream
+++ b/StanHeaders/inst/include/upstream
@@ -1 +1 @@
-Subproject commit 4a0c0e8828ee8a9fd42d933ff9706760f461e2f4
+Subproject commit 21cef932e17ca64cf60926aea1fb156fa0826563