diff --git a/changelog.d/13791.removal b/changelog.d/13791.removal
new file mode 100644
index 0000000000..283226b63e
--- /dev/null
+++ b/changelog.d/13791.removal
@@ -0,0 +1 @@
+Don't include redundant `prev_state` in new events. Contributed by Denis Kariakin (@dakariakin).
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 746bd3978d..e2ee10dd3d 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -167,7 +167,6 @@ class EventBuilder:
             "content": self.content,
             "unsigned": self.unsigned,
             "depth": depth,
-            "prev_state": [],
         }
 
         if self.is_state():
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 4a4289ee7c..464672a3da 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -906,9 +906,6 @@ class FederationClient(FederationBase):
             # The protoevent received over the JSON wire may not have all
             # the required fields. Lets just gloss over that because
             # there's some we never care about
-            if "prev_state" not in pdu_dict:
-                pdu_dict["prev_state"] = []
-
             ev = builder.create_local_event_from_event_dict(
                 self._clock,
                 self.hostname,