diff --git a/tildes/tildes/__init__.py b/tildes/tildes/__init__.py
index 8528847..fa0f314 100644
--- a/tildes/tildes/__init__.py
+++ b/tildes/tildes/__init__.py
@@ -32,6 +32,7 @@ def main(global_config: Dict[str, str], **settings: str) -> PrefixMiddleware:
     config.include("tildes.jinja")
     config.include("tildes.json")
     config.include("tildes.routes")
+    config.include("tildes.tweens")
 
     config.add_webasset("javascript", Bundle(output="js/tildes.js"))
     config.add_webasset("javascript-third-party", Bundle(output="js/third_party.js"))
@@ -39,10 +40,6 @@ def main(global_config: Dict[str, str], **settings: str) -> PrefixMiddleware:
 
     config.scan("tildes.views")
 
-    config.add_tween("tildes.tweens.http_method_tween_factory")
-    config.add_tween("tildes.tweens.metrics_tween_factory")
-    config.add_tween("tildes.tweens.theme_cookie_tween_factory")
-
     config.add_static_view("images", "/images")
 
     config.add_request_method(is_safe_request_method, "is_safe_method", reify=True)
diff --git a/tildes/tildes/tweens.py b/tildes/tildes/tweens.py
index 00d44ca..8c5a385 100644
--- a/tildes/tildes/tweens.py
+++ b/tildes/tildes/tweens.py
@@ -7,6 +7,7 @@ from time import time
 from typing import Callable
 
 from prometheus_client import Histogram
+from pyramid.config import Configurator
 from pyramid.registry import Registry
 from pyramid.request import Request
 from pyramid.response import Response
@@ -115,3 +116,10 @@ def theme_cookie_tween_factory(handler: Callable, registry: Registry) -> Callabl
         return response
 
     return theme_cookie_tween
+
+
+def includeme(config: Configurator) -> None:
+    """Attach Tildes tweens to the Pyramid config."""
+    config.add_tween("tildes.tweens.http_method_tween_factory")
+    config.add_tween("tildes.tweens.metrics_tween_factory")
+    config.add_tween("tildes.tweens.theme_cookie_tween_factory")