diff --git a/content/install-hook-userstyles.js b/content/install-hook-userstyles.js
index 5fe0ca46..b133eaa6 100644
--- a/content/install-hook-userstyles.js
+++ b/content/install-hook-userstyles.js
@@ -223,6 +223,8 @@
           url,
           method: 'download',
           timeout: 60e3,
+          // USO can't handle POST requests for style json
+          body: null,
         }, result => {
           const error = result && result.__ERROR__;
           if (error) {