diff --git a/echo.go b/echo.go
index 9ae2ed4e5..fc7e116f0 100644
--- a/echo.go
+++ b/echo.go
@@ -207,6 +207,7 @@ const (
 	HeaderIfModifiedSince     = "If-Modified-Since"
 	HeaderLastModified        = "Last-Modified"
 	HeaderLocation            = "Location"
+	HeaderRetryAfter          = "Retry-After"
 	HeaderUpgrade             = "Upgrade"
 	HeaderVary                = "Vary"
 	HeaderWWWAuthenticate     = "WWW-Authenticate"