diff --git a/buffer/pool.go b/buffer/pool.go
index 3e7d2b62..3265283f 100644
--- a/buffer/pool.go
+++ b/buffer/pool.go
@@ -5,6 +5,8 @@ import (
 )
 
 type Pool struct {
+	// A Pool must not be copied after first use.
+	// https://golang.org/pkg/sync/#Pool
 	buffers sync.Pool
 }