diff --git a/pkg/controller/operator_config.go b/pkg/controller/operator_config.go
index c6f10faa0..03602c3bd 100644
--- a/pkg/controller/operator_config.go
+++ b/pkg/controller/operator_config.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	acidv1 "github.com/zalando/postgres-operator/pkg/apis/acid.zalan.do/v1"
+	"github.com/zalando/postgres-operator/pkg/util"
 	"github.com/zalando/postgres-operator/pkg/util/config"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
@@ -50,7 +51,7 @@ func (c *Controller) importConfigurationFromCRD(fromCRD *acidv1.OperatorConfigur
 	result.PodTerminateGracePeriod = time.Duration(fromCRD.Kubernetes.PodTerminateGracePeriod)
 	result.SpiloPrivileged = fromCRD.Kubernetes.SpiloPrivileged
 	result.SpiloFSGroup = fromCRD.Kubernetes.SpiloFSGroup
-	result.ClusterDomain = fromCRD.Kubernetes.ClusterDomain
+	result.ClusterDomain = util.Coalesce(fromCRD.Kubernetes.ClusterDomain, "cluster.local")
 	result.WatchedNamespace = fromCRD.Kubernetes.WatchedNamespace
 	result.PDBNameFormat = fromCRD.Kubernetes.PDBNameFormat
 	result.EnablePodDisruptionBudget = fromCRD.Kubernetes.EnablePodDisruptionBudget