diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 2afddf58d1..e5450edfb6 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -377,7 +377,7 @@ jobs:
       # Run Complement
       - run: |
           set -o pipefail
-          go test -v -json -tags synapse_blacklist,msc2403,msc2716,msc3030 ./tests/... 2>&1 | gotestfmt
+          go test -v -json -tags synapse_blacklist,msc2716,msc3030 ./tests/... 2>&1 | gotestfmt
         shell: bash
         name: Run Complement Tests
         env:
diff --git a/changelog.d/12165.misc b/changelog.d/12165.misc
new file mode 100644
index 0000000000..4b80b0562e
--- /dev/null
+++ b/changelog.d/12165.misc
@@ -0,0 +1 @@
+Remove lingering unstable references to MSC2403 (knocking).
diff --git a/scripts-dev/complement.sh b/scripts-dev/complement.sh
index 0a79a4063f..d1b59ff040 100755
--- a/scripts-dev/complement.sh
+++ b/scripts-dev/complement.sh
@@ -71,4 +71,4 @@ fi
 
 # Run the tests!
 echo "Images built; running complement"
-go test -v -tags synapse_blacklist,msc2403,msc2716,msc3030 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests/...
+go test -v -tags synapse_blacklist,msc2716,msc3030 -count=1 $EXTRA_COMPLEMENT_ARGS ./tests/...
diff --git a/tests/federation/transport/test_knocking.py b/tests/federation/transport/test_knocking.py
index 648a01618e..d21c11b716 100644
--- a/tests/federation/transport/test_knocking.py
+++ b/tests/federation/transport/test_knocking.py
@@ -23,7 +23,7 @@ from synapse.server import HomeServer
 from synapse.types import RoomAlias
 
 from tests.test_utils import event_injection
-from tests.unittest import FederatingHomeserverTestCase, TestCase, override_config
+from tests.unittest import FederatingHomeserverTestCase, TestCase
 
 
 class KnockingStrippedStateEventHelperMixin(TestCase):
@@ -221,7 +221,6 @@ class FederationKnockingTestCase(
 
         return super().prepare(reactor, clock, homeserver)
 
-    @override_config({"experimental_features": {"msc2403_enabled": True}})
     def test_room_state_returned_when_knocking(self):
         """
         Tests that specific, stripped state events from a room are returned after
diff --git a/tests/rest/client/test_sync.py b/tests/rest/client/test_sync.py
index f0f3a54f82..3cebbd18f0 100644
--- a/tests/rest/client/test_sync.py
+++ b/tests/rest/client/test_sync.py
@@ -341,7 +341,6 @@ class SyncKnockTestCase(
             hs, self.room_id, self.user_id
         )
 
-    @override_config({"experimental_features": {"msc2403_enabled": True}})
     def test_knock_room_state(self) -> None:
         """Tests that /sync returns state from a room after knocking on it."""
         # Knock on a room