diff --git a/src/net/http/cgi/host.go b/src/net/http/cgi/host.go
index 073952a7bd..085658ee7a 100644
--- a/src/net/http/cgi/host.go
+++ b/src/net/http/cgi/host.go
@@ -132,6 +132,9 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
 	}
 
 	port := "80"
+	if req.TLS != nil {
+		port = "443"
+	}
 	if matches := trailingPort.FindStringSubmatch(req.Host); len(matches) != 0 {
 		port = matches[1]
 	}