diff --git a/Makefile b/Makefile
index d85b74ed3..f67bbe62b 100644
--- a/Makefile
+++ b/Makefile
@@ -69,8 +69,8 @@ $(GENERATED_CRDS): $(GENERATED)
 	go tool controller-gen crd:crdVersions=v1,allowDangerousTypes=true paths=./pkg/apis/acid.zalan.do/... output:crd:dir=manifests
 	@mv manifests/acid.zalan.do_postgresqls.yaml manifests/postgresql.crd.yaml
 	@# hack to use lowercase kind and listKind
-	@sed -i -e 's/kind: Postgresql/kind: postgresql/' manifests/postgresql.crd.yaml
-	@sed -i -e 's/listKind: PostgresqlList/listKind: postgresqlList/' manifests/postgresql.crd.yaml
+	@sed -i.bak 's/kind: Postgresql/kind: postgresql/' manifests/postgresql.crd.yaml && rm manifests/postgresql.crd.yaml.bak
+	@sed -i.bak 's/listKind: PostgresqlList/listKind: postgresqlList/' manifests/postgresql.crd.yaml && rm manifests/postgresql.crd.yaml.bak
 	@hack/adjust_postgresql_crd.sh
 	@mv manifests/acid.zalan.do_operatorconfigurations.yaml manifests/operatorconfiguration.crd.yaml
 	@mv manifests/acid.zalan.do_postgresteams.yaml manifests/postgresteam.crd.yaml
diff --git a/hack/adjust_postgresql_crd.sh b/hack/adjust_postgresql_crd.sh
index d06b74a2d..ff111b621 100755
--- a/hack/adjust_postgresql_crd.sh
+++ b/hack/adjust_postgresql_crd.sh
@@ -13,12 +13,12 @@
 
 file="${1:-"manifests/postgresql.crd.yaml"}"
 
-sed -i '/^[[:space:]]*standby:$/{
+sed -i '' '/^[[:space:]]*standby:$/{
     # Capture the indentation
     s/^\([[:space:]]*\)standby:$/\1standby:\n\1  anyOf:\n\1  - required:\n\1    - s3_wal_path\n\1  - required:\n\1    - gs_wal_path\n\1  - required:\n\1    - standby_host\n\1  not:\n\1    required:\n\1    - s3_wal_path\n\1    - gs_wal_path/
 }' "$file"
 
-sed -i '/^[[:space:]]*maintenanceWindows:$/{
+sed -i '' '/^[[:space:]]*maintenanceWindows:$/{
     # Capture the indentation
     s/^\([[:space:]]*\)maintenanceWindows:$/\1maintenanceWindows:\n\1  items:\n\1    pattern: '\''^\\ *((Mon|Tue|Wed|Thu|Fri|Sat|Sun):(2[0-3]|[01]?\\d):([0-5]?\\d)|(2[0-3]|[01]?\\d):([0-5]?\\d))-((2[0-3]|[01]?\\d):([0-5]?\\d)|(2[0-3]|[01]?\\d):([0-5]?\\d))\\ *$'\''\n\1    type: string/
 }' "$file"
diff --git a/pkg/cluster/resources.go b/pkg/cluster/resources.go
index b83067ac9..ba23616ab 100644
--- a/pkg/cluster/resources.go
+++ b/pkg/cluster/resources.go
@@ -11,6 +11,7 @@ import (
 	v1 "k8s.io/api/core/v1"
 	policyv1 "k8s.io/api/policy/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
 	"k8s.io/apimachinery/pkg/types"
 
 	"github.com/zalando/postgres-operator/pkg/util"
@@ -211,11 +212,17 @@ func (c *Cluster) updateStatefulSet(newStatefulSet *appsv1.StatefulSet) error {
 }
 
 // replaceStatefulSet deletes an old StatefulSet and creates the new using spec in the PostgreSQL CRD.
-func (c *Cluster) relabelPodsForSelector(newSelector map[string]string) error {
-	pods, err := c.listPods()
+func (c *Cluster) relabelPodsForSelector(oldSelector, newSelector map[string]string) error {
+	// list pods using the OLD selector — at this point c.labelsSet already reflects
+	// the new cluster_labels config, so listPods() would find nothing.
+	listOptions := metav1.ListOptions{
+		LabelSelector: labels.Set(oldSelector).String(),
+	}
+	podList, err := c.KubeClient.Pods(c.Namespace).List(context.TODO(), listOptions)
 	if err != nil {
 		return fmt.Errorf("could not list pods for relabeling: %v", err)
 	}
+	pods := podList.Items
 
 	for _, pod := range pods {
 		// only patch pods that are missing one or more of the new selector labels
@@ -255,7 +262,7 @@ func (c *Cluster) replaceStatefulSet(newStatefulSet *appsv1.StatefulSet) error {
 	// If the new selector has labels the existing pods don't carry, relabel them first
 	// so the new StatefulSet can adopt them after the cascade=orphan delete.
 	if !util.MapContains(c.Statefulset.Spec.Selector.MatchLabels, newStatefulSet.Spec.Selector.MatchLabels) {
-		if err := c.relabelPodsForSelector(newStatefulSet.Spec.Selector.MatchLabels); err != nil {
+		if err := c.relabelPodsForSelector(c.Statefulset.Spec.Selector.MatchLabels, newStatefulSet.Spec.Selector.MatchLabels); err != nil {
 			return fmt.Errorf("could not relabel pods before statefulset replacement: %v", err)
 		}
 	}