diff --git a/StanHeaders/inst/include/upstream b/StanHeaders/inst/include/upstream
index 9b2ae9914..90a704a3c 160000
--- a/StanHeaders/inst/include/upstream
+++ b/StanHeaders/inst/include/upstream
@@ -1 +1 @@
-Subproject commit 9b2ae991405db7bf21e261f76f7f9a2fdcab9762
+Subproject commit 90a704a3c60533383eda739f04c400fd0f1ddb00