diff --git a/theseus/index.js b/theseus/index.js
index 4f366b5..c44406b 100644
--- a/theseus/index.js
+++ b/theseus/index.js
@@ -176,7 +176,9 @@ module.exports = {
       });
     });
 
-    api.registerSidebarPanel({ id: "main", title: "Pithos", page: "ui/index.html" });
+    // Left edge, beside the quick links. Theseus builds without left panels
+    // ignore `side` and show it in the right sidebar.
+    api.registerSidebarPanel({ id: "main", title: "Pithos", page: "ui/index.html", side: "left" });
 
     // The host has no quit hook for add-ons; without this an s3d we started
     // would outlive Theseus.