diff --git a/changelog.d/8373.bugfix b/changelog.d/8373.bugfix
new file mode 100644
index 0000000000000000000000000000000000000000..e9d66a2088c4e31a4b02389abd7a157fb3dcf446
--- /dev/null
+++ b/changelog.d/8373.bugfix
@@ -0,0 +1 @@
+Include `guest_access` in the fields that are checked for null bytes when updating `room_stats_state`. Broke in v1.7.2.
\ No newline at end of file
diff --git a/synapse/storage/databases/main/stats.py b/synapse/storage/databases/main/stats.py
index d7816a8606ab2088668e9a150d3b97a11aa86bfc..5beb302be3434fab293e8fb0b9c9c25d14a9601b 100644
--- a/synapse/storage/databases/main/stats.py
+++ b/synapse/storage/databases/main/stats.py
@@ -210,6 +210,7 @@ class StatsStore(StateDeltasStore):
         * topic
         * avatar
         * canonical_alias
+        * guest_access
 
         A is_federatable key can also be included with a boolean value.
 
@@ -234,6 +235,7 @@ class StatsStore(StateDeltasStore):
             "topic",
             "avatar",
             "canonical_alias",
+            "guest_access",
         ):
             field = fields.get(col, sentinel)
             if field is not sentinel and (not isinstance(field, str) or "\0" in field):