diff --git a/synapse/storage/databases/main/sliding_sync.py b/synapse/storage/databases/main/sliding_sync.py
index 6a62b11d1e..72ec8e6b90 100644
--- a/synapse/storage/databases/main/sliding_sync.py
+++ b/synapse/storage/databases/main/sliding_sync.py
@@ -492,7 +492,7 @@ class PerConnectionStateDB:
     """An equivalent to `PerConnectionState` that holds data in a format stored
     in the DB.
 
-    The principle difference is that the tokens for the different streams are
+    The principal difference is that the tokens for the different streams are
     serialized to strings.
 
     When persisting this *only* contains updates to the state.