1 files changed, 2 insertions, 1 deletions
diff --git a/synapse/util/frozenutils.py b/synapse/util/frozenutils.py
index 9c405eb4d7..7223af1a36 100644
--- a/synapse/util/frozenutils.py
+++ b/synapse/util/frozenutils.py
@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import collections.abc
 from typing import Any
 
 from frozendict import frozendict
@@ -35,7 +36,7 @@ def freeze(o: Any) -> Any:
 
 
 def unfreeze(o: Any) -> Any:
-    if isinstance(o, (dict, frozendict)):
+    if isinstance(o, collections.abc.Mapping):
         return {k: unfreeze(v) for k, v in o.items()}
 
     if isinstance(o, (bytes, str)):