diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
index 251d3afcf..90fb6c133 100644
--- a/synapse/replication/tcp/client.py
+++ b/synapse/replication/tcp/client.py
@@ -175,7 +175,7 @@ class ReplicationClientHandler(object):
     def send_invalidate_cache(self, cache_func, keys):
         """Poke the master to invalidate a cache.
         """
-        cmd = InvalidateCacheCommand(cache_func, keys)
+        cmd = InvalidateCacheCommand(cache_func.__name__, keys)
         self.send_command(cmd)
 
     def await_sync(self, data):