diff --git a/log/doc.go b/log/doc.go
index de9de4f..81a60ee 100644
--- a/log/doc.go
+++ b/log/doc.go
@@ -16,5 +16,6 @@
 //  h := NewStreamHandler(os.Stdout)
 //  l := log.NewDefault(h)
 //  l.Info("hello world")
+//  l.Infof("%s %d", "hello", 123)
 //
 package log