diff --git a/tailbone/app.py b/tailbone/app.py
index abf2fa09..63610f85 100644
--- a/tailbone/app.py
+++ b/tailbone/app.py
@@ -123,6 +123,9 @@ def make_pyramid_config(settings, configure_csrf=True):
         config.set_root_factory(Root)
     else:
 
+        # declare this web app of the "classic" variety
+        settings.setdefault('tailbone.classic', 'true')
+
         # we want the new themes feature!
         establish_theme(settings)
 
@@ -130,6 +133,7 @@ def make_pyramid_config(settings, configure_csrf=True):
         config = Configurator(settings=settings, root_factory=Root)
 
     # add rattail config directly to registry
+    # TODO: why on earth do we do this again?
     config.registry['rattail_config'] = rattail_config
 
     # configure user authorization / authentication
diff --git a/tailbone/subscribers.py b/tailbone/subscribers.py
index 9b56335a..8d10eb0b 100644
--- a/tailbone/subscribers.py
+++ b/tailbone/subscribers.py
@@ -98,10 +98,14 @@ def new_request(event):
 
     request.set_property(user, reify=True)
 
-    def use_oruga(request):
-        return should_use_oruga(request)
+    # nb. only add oruga check for "classic" web app
+    classic = rattail_config.parse_bool(request.registry.settings.get('tailbone.classic'))
+    if classic:
 
-    request.set_property(use_oruga, reify=True)
+        def use_oruga(request):
+            return should_use_oruga(request)
+
+        request.set_property(use_oruga, reify=True)
 
     # assign client IP address to the session, for sake of versioning
     Session().continuum_remote_addr = request.client_addr
@@ -173,11 +177,11 @@ def before_render(event):
     renderer_globals['colander'] = colander
     renderer_globals['deform'] = deform
     renderer_globals['csrf_header_name'] = csrf_header_name(request.rattail_config)
-    renderer_globals['b'] = 'o' if request.use_oruga else 'b' # for buefy
 
     # theme  - we only want do this for classic web app, *not* API
     # TODO: so, clearly we need a better way to distinguish the two
     if 'tailbone.theme' in request.registry.settings:
+        renderer_globals['b'] = 'o' if request.use_oruga else 'b' # for buefy
         renderer_globals['theme'] = request.registry.settings['tailbone.theme']
         # note, this is just a global flag; user still needs permission to see picker
         expose_picker = request.rattail_config.getbool('tailbone', 'themes.expose_picker',