diff --git a/README.md b/README.md
index bf4f6efd7..b50d2a176 100644
--- a/README.md
+++ b/README.md
@@ -178,6 +178,8 @@ data:
 
 This ConfigMap is then added as a source of environment variables to the Postgres StatefulSet/pods.
 
+:exclamation: Note that there are environment variables defined by the operator itself in order to pass parameters to the Spilo image. The values from the operator for those variables will take precedence over those defined in the `pod_environment_configmap`.
+
 # Setup development environment
 
 The following steps guide you through the setup to work on the operator itself.
diff --git a/pkg/cluster/k8sres.go b/pkg/cluster/k8sres.go
index 0bbed17b7..d8ed0435d 100644
--- a/pkg/cluster/k8sres.go
+++ b/pkg/cluster/k8sres.go
@@ -282,7 +282,7 @@ func (c *Cluster) generatePodTemplate(resourceRequirements *v1.ResourceRequireme
 	patroniParameters *spec.Patroni,
 	cloneDescription *spec.CloneDescription,
 	dockerImage *string,
-	extraEnv map[string]string) *v1.PodTemplateSpec {
+	customPodEnvVars map[string]string) *v1.PodTemplateSpec {
 	spiloConfiguration := c.generateSpiloJSONConfiguration(pgParameters, patroniParameters)
 
 	envVars := []v1.EnvVar{
@@ -373,14 +373,17 @@ func (c *Cluster) generatePodTemplate(resourceRequirements *v1.ResourceRequireme
 	for _, envVar := range envVars {
 		envVarsMap[envVar.Name] = envVar.Value
 	}
-	for name := range extraEnv {
+	for name := range customPodEnvVars {
 		if _, ok := envVarsMap[name]; !ok {
 			names = append(names, name)
+		} else {
+			c.logger.Warningf("variable %q value from %q is ignored: conflict with the definition from the operator",
+				name, c.OpConfig.PodEnvironmentConfigMap)
 		}
 	}
 	sort.Strings(names)
 	for _, name := range names {
-		envVars = append(envVars, v1.EnvVar{Name: name, Value: extraEnv[name]})
+		envVars = append(envVars, v1.EnvVar{Name: name, Value: customPodEnvVars[name]})
 	}
 
 	privilegedMode := true
@@ -447,15 +450,15 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 	if err != nil {
 		return nil, fmt.Errorf("could not generate resource requirements: %v", err)
 	}
-	var extraEnv map[string]string
+	var customPodEnvVars map[string]string
 	if c.OpConfig.PodEnvironmentConfigMap != "" {
 		if cm, err := c.KubeClient.ConfigMaps(c.Namespace).Get(c.OpConfig.PodEnvironmentConfigMap, metav1.GetOptions{}); err != nil {
 			return nil, fmt.Errorf("could not read PodEnvironmentConfigMap: %v", err)
 		} else {
-			extraEnv = cm.Data
+			customPodEnvVars = cm.Data
 		}
 	}
-	podTemplate := c.generatePodTemplate(resourceRequirements, &spec.Tolerations, &spec.PostgresqlParam, &spec.Patroni, &spec.Clone, &spec.DockerImage, extraEnv)
+	podTemplate := c.generatePodTemplate(resourceRequirements, &spec.Tolerations, &spec.PostgresqlParam, &spec.Patroni, &spec.Clone, &spec.DockerImage, customPodEnvVars)
 	volumeClaimTemplate, err := generatePersistentVolumeClaimTemplate(spec.Volume.Size, spec.Volume.StorageClass)
 	if err != nil {
 		return nil, fmt.Errorf("could not generate volume claim template: %v", err)