diff --git a/plain/plain/http/response.py b/plain/plain/http/response.py
index e8aec64022..2208212b90 100644
--- a/plain/plain/http/response.py
+++ b/plain/plain/http/response.py
@@ -798,7 +798,10 @@ def __init__(
 
 
 class NotAllowedResponse(Response):
-    """HTTP 405 response"""
+    """HTTP 405 response.
+
+    The constructor is pinned: no status_code parameter, so this class
+    always means exactly "405 method not allowed"."""
 
     status_code = 405
 
@@ -807,14 +810,12 @@ def __init__(
         permitted_methods: list[str],
         *,
         content_type: str | None = None,
-        status_code: int | None = None,
         reason: str | None = None,
         charset: str | None = None,
         headers: dict[str, Any] | None = None,
     ):
         super().__init__(
             content_type=content_type,
-            status_code=status_code,
             reason=reason,
             charset=charset,
             headers=headers,
diff --git a/plain/tests/public/test_http_bodiless_responses.py b/plain/tests/public/test_http_bodiless_responses.py
index a063ca4b8b..0f07289248 100644
--- a/plain/tests/public/test_http_bodiless_responses.py
+++ b/plain/tests/public/test_http_bodiless_responses.py
@@ -14,6 +14,7 @@
     FileResponse,
     HTTPException,
     JsonResponse,
+    NotAllowedResponse,
     NotModifiedResponse,
     Response,
     StreamingResponse,
@@ -158,6 +159,13 @@ def test_not_modified_response_signature_is_pinned():
         NotModifiedResponse(status_code=200)  # ty: ignore[unknown-argument]
 
 
+def test_not_allowed_response_signature_is_pinned():
+    # No status_code parameter — this class always means exactly "405
+    # method not allowed".
+    with pytest.raises(TypeError):
+        NotAllowedResponse(["GET"], status_code=200)  # ty: ignore[unknown-argument]
+
+
 def test_setting_content_after_bodiless_status_raises():
     response = Response(status_code=204)
     with pytest.raises(ValueError, match="cannot have a body"):