diff --git a/changelog.d/11558.misc b/changelog.d/11558.misc
new file mode 100644
index 0000000000..7c334f17e0
--- /dev/null
+++ b/changelog.d/11558.misc
@@ -0,0 +1 @@
+Stop populating unused database column `state_events.prev_state`.
diff --git a/synapse/storage/databases/main/events.py b/synapse/storage/databases/main/events.py
index f1f4ce5e07..eed453d836 100644
--- a/synapse/storage/databases/main/events.py
+++ b/synapse/storage/databases/main/events.py
@@ -1410,10 +1410,6 @@ class PersistEventsStore:
                 "state_key": event.state_key,
             }
 
-            # TODO: How does this work with backfilling?
-            if hasattr(event, "replaces_state"):
-                vals["prev_state"] = event.replaces_state
-
             state_values.append(vals)
 
         self.db_pool.simple_insert_many_txn(
diff --git a/synapse/storage/schema/__init__.py b/synapse/storage/schema/__init__.py
index 50d08094d5..2a3d47185a 100644
--- a/synapse/storage/schema/__init__.py
+++ b/synapse/storage/schema/__init__.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-SCHEMA_VERSION = 66  # remember to update the list below when updating
+SCHEMA_VERSION = 67  # remember to update the list below when updating
 """Represents the expectations made by the codebase about the database schema
 
 This should be incremented whenever the codebase changes its requirements on the
@@ -50,6 +50,9 @@ Changes in SCHEMA_VERSION = 65:
 Changes in SCHEMA_VERSION = 66:
     - Queries on state_key columns are now disambiguated (ie, the codebase can handle
       the `events` table having a `state_key` column).
+
+Changes in SCHEMA_VERSION = 67:
+    - state_events.prev_state is no longer written to.
 """