1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py

index 5eaf3151ce..3c86cbc546 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -76,7 +76,7 @@ MAXINT = sys.maxsize
 _next_id = 1
 
 
-@attr.s(frozen=True)
+@attr.s(slots=True, frozen=True)
 class MatrixFederationRequest:
     method = attr.ib()
     """HTTP method