diff --git a/progress.go b/progress.go
index 983b9e2..7042893 100644
--- a/progress.go
+++ b/progress.go
@@ -129,6 +129,7 @@
 	return p
 }
 
+// BeforeRenderFunc accepts a func, which gets called before render process.
 func (p *Progress) BeforeRenderFunc(f BeforeRender) *Progress {
 	if IsClosed(p.done) {
 		panic(ErrCallAfterStop)