1 files changed, 2 insertions, 1 deletions
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index e6f94e68af..154a7c0198 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -247,6 +247,7 @@ def room_version_to_event_format(room_version):
         int
     """
     if room_version not in KNOWN_ROOM_VERSIONS:
-        raise
+        # We should have already checked version, so this should not happen
+        raise RuntimeError("Unrecognized room version %s" % (room_version,))
 
     return EventFormatVersions.V1