diff --git a/src/snek/system/middleware.py b/src/snek/system/middleware.py
index 023f5ba..710ec3a 100644
--- a/src/snek/system/middleware.py
+++ b/src/snek/system/middleware.py
@@ -13,7 +13,7 @@ def generate_nonce():
     return secrets.token_hex(16)
 
 @web.middleware
-async def csp_middleware(app, handler):
+async def csp_middleware(request, handler):
     response = await handler(request)
     nonce = generate_nonce()
     response.headers['Content-Security-Policy'] = csp_policy.format(nonce=nonce)