diff --git a/tests/federation/transport/test_client.py b/tests/federation/transport/test_client.py
index 3b0a2201fb..881baa02a9 100644
--- a/tests/federation/transport/test_client.py
+++ b/tests/federation/transport/test_client.py
@@ -40,7 +40,7 @@ class SendJoinParserTestCase(TestCase):
             "sender": "@user:example.org",
             "depth": 1,
             "origin_server_ts": 1,
-            "hashes": {"sha256": ""},
+            "hashes": {},
             "auth_events": [],
             "prev_events": [],
         }
diff --git a/tests/rest/client/test_third_party_rules.py b/tests/rest/client/test_third_party_rules.py
index adb3855a06..b4fa71ece8 100644
--- a/tests/rest/client/test_third_party_rules.py
+++ b/tests/rest/client/test_third_party_rules.py
@@ -532,7 +532,7 @@ class ThirdPartyRulesTestCase(unittest.FederatingHomeserverTestCase):
                     "origin_server_ts": self.clock.time_msec(),
                     "prev_events": [],
                     "auth_events": [],
-                    "hashes": {"sha256": ""},
+                    "hashes": {},
                     "signatures": {},
                     "unsigned": {},
                 }
diff --git a/tests/state/test_v21.py b/tests/state/test_v21.py
index 3b9bb212aa..6b4d2837ab 100644
--- a/tests/state/test_v21.py
+++ b/tests/state/test_v21.py
@@ -495,7 +495,7 @@ class StateResV21TestCase(unittest.HomeserverTestCase):
             "prev_events": prev_events,
             "auth_events": auth_events,
             "origin_server_ts": monotonic_timestamp(),
-            "hashes": {"sha256": ""},
+            "hashes": {},
         }
         if event_type != EventTypes.Create:
             if room_id is None:
diff --git a/tests/test_utils/event_builders.py b/tests/test_utils/event_builders.py
index 00fdcac605..c9c8d95044 100644
--- a/tests/test_utils/event_builders.py
+++ b/tests/test_utils/event_builders.py
@@ -32,7 +32,7 @@ def default_event_fields(room_version: RoomVersion) -> JsonDict:
         "content": {},
         "depth": 1,
         "origin_server_ts": 1,
-        "hashes": {"sha256": ""},
+        "hashes": {},
         "prev_events": [],
         "room_id": "!test:test",
     }