diff --git a/blueprints/tasks.py b/blueprints/tasks.py
index 2d8ebfb..d98542b 100644
--- a/blueprints/tasks.py
+++ b/blueprints/tasks.py
@@ -10,13 +10,13 @@ from little_boxes import activitypub as ap
 from little_boxes.errors import ActivityGoneError
 from little_boxes.errors import ActivityNotFoundError
 from little_boxes.errors import NotAnActivityError
-from little_boxes.httpsig import HTTPSigAuth
 from requests.exceptions import HTTPError
 
 import config
 from config import DB
 from config import MEDIA_CACHE
 from core import gc
+from core.activitypub import SIG_AUTH
 from core.activitypub import Box
 from core.activitypub import _actor_hash
 from core.activitypub import _add_answers_to_question
@@ -41,8 +41,6 @@ from core.tasks import Tasks
 from utils import now
 from utils import opengraph
 
-SIG_AUTH = HTTPSigAuth(config.KEY)
-
 blueprint = flask.Blueprint("tasks", __name__)
 
 
diff --git a/core/activitypub.py b/core/activitypub.py
index 4d1e728..fbaee28 100644
--- a/core/activitypub.py
+++ b/core/activitypub.py
@@ -23,11 +23,13 @@ from little_boxes.activitypub import clean_activity
 from little_boxes.activitypub import format_datetime
 from little_boxes.backend import Backend
 from little_boxes.errors import ActivityGoneError
+from little_boxes.httpsig import HTTPSigAuth
 
 from config import BASE_URL
 from config import DB
 from config import EXTRA_INBOXES
 from config import ID
+from config import KEY
 from config import ME
 from config import USER_AGENT
 from core.db import update_many_activities
@@ -41,6 +43,7 @@ logger = logging.getLogger(__name__)
 
 _NewMeta = Dict[str, Any]
 
+SIG_AUTH = HTTPSigAuth(KEY)
 
 _ACTIVITY_CACHE_ENABLED = True
 ACTORS_CACHE = LRUCache(maxsize=256)
@@ -364,7 +367,8 @@ class MicroblogPubBackend(Backend):
             data = self._fetch_iri(iri)
             logger.debug(f"_fetch_iri({iri!r}) == {data!r}")
         else:
-            data = super().fetch_iri(iri)
+            # Pass the SIG_AUTH to enable "authenticated fetch"
+            data = super().fetch_iri(iri, auth=SIG_AUTH)
             logger.debug(f"fetch_iri({iri!r}) == {data!r}")
 
         return data