diff --git a/source/skipper_routegroup.go b/source/skipper_routegroup.go
index 2c3475ac4..3854722cc 100644
--- a/source/skipper_routegroup.go
+++ b/source/skipper_routegroup.go
@@ -210,7 +210,8 @@ func NewRouteGroupSource(timeout time.Duration, token, tokenPath, apiServerURL,
 	apiServer := u.String()
 	// strip port if well known port, because of TLS certificate match
 	if u.Scheme == "https" && u.Port() == "443" {
-		apiServer = "https://" + u.Hostname()
+		// correctly handle IPv6 addresses by keeping surrounding `[]`.
+		apiServer = "https://" + strings.TrimSuffix(u.Host, ":443")
 	}
 
 	sc := &routeGroupSource{