diff --git a/lib/gat/handlers/discovery/discoverers/zalando_operator/discoverer.go b/lib/gat/handlers/discovery/discoverers/zalando_operator/discoverer.go
index 8f0567b4398d334c0b6216ad92600397cfb6297b..9e2fc4e4e4f381e175d5fa1758238a75e66e7019 100644
--- a/lib/gat/handlers/discovery/discoverers/zalando_operator/discoverer.go
+++ b/lib/gat/handlers/discovery/discoverers/zalando_operator/discoverer.go
@@ -150,6 +150,9 @@ func (T *Discoverer) Provision(ctx caddy.Context) error {
 }
 
 func (T *Discoverer) Cleanup() error {
+	if T.done == nil {
+		return nil
+	}
 	close(T.done)
 	return nil
 }