diff --git a/mvcc/watchable_store.go b/mvcc/watchable_store.go
index 8f12bddba88..a2c6528d7dc 100644
--- a/mvcc/watchable_store.go
+++ b/mvcc/watchable_store.go
@@ -28,9 +28,8 @@ import (
 var (
 	// chanBufLen is the length of the buffered chan
 	// for sending out watched events.
-	// TODO: find a good buf value. 1024 is just a random one that
-	// seems to be reasonable.
-	chanBufLen = 1024
+	// See https://github.com/etcd-io/etcd/issues/11906 for more detail.
+	chanBufLen = 128
 
 	// maxWatchersPerSync is the number of watchers to sync in a single batch
 	maxWatchersPerSync = 512