diff --git a/pkg/zones/env.go b/pkg/zones/env.go
index c51bf83..32e30a4 100644
--- a/pkg/zones/env.go
+++ b/pkg/zones/env.go
@@ -22,11 +22,23 @@ func (m *Zones) Env(export bool) *Env {
 	}
 }
 
+// Zones returns the list of Zone IDs
+func (m *Env) Zones() []int {
+	var zones []int
+
+	m.ForEachZone(func(z *Zone) bool {
+		zones = append(zones, z.ID)
+		return false
+	})
+
+	return zones
+}
+
 // WriteTo generates environment variables for shell scripts
 func (m *Env) WriteTo(w io.Writer) (int64, error) {
 	var buf bytes.Buffer
 
-	m.writeEnvVarFn(&buf, genEnvZones, "ZONES")
+	m.writeEnvVar(&buf, genEnvInts(m.Zones()), "ZONES")
 	m.ForEachZone(func(z *Zone) bool {
 		m.writeEnvZone(&buf, z)
 		return false
@@ -51,16 +63,6 @@ func (m *Env) writeEnvZone(w io.Writer, z *Zone) {
 	}
 }
 
-func (m *Env) writeEnvVarFn(w io.Writer, fn func(*Env) string, name string, args ...any) {
-	var value string
-
-	if fn != nil {
-		value = fn(m)
-	}
-
-	m.writeEnvVar(w, value, name, args...)
-}
-
 func (m *Env) writeEnvVar(w io.Writer, value string, name string, args ...any) {
 	var prefix string
 
@@ -79,23 +81,27 @@ func (m *Env) writeEnvVar(w io.Writer, value string, name string, args ...any) {
 	}
 }
 
-func genEnvZones(m *Env) string {
-	var s []string
-
-	m.ForEachZone(func(z *Zone) bool {
-		s = append(s, fmt.Sprintf("%v", z.ID))
-		return false
-	})
+func genEnvInts(a []int) string {
+	s := make([]string, len(a))
+	for i, id := range a {
+		s[i] = fmt.Sprintf("%v", id)
+	}
 
 	return strings.Join(s, " ")
 }
 
 func genEnvZoneNodes(z *Zone) string {
-	s := make([]string, 0, len(z.Machines))
-	for _, p := range z.Machines {
-		s = append(s, p.Name)
+	if n := z.Len(); n > 0 {
+		s := make([]string, 0, n)
+
+		z.ForEachMachine(func(p *Machine) bool {
+			s = append(s, p.Name)
+			return false
+		})
+
+		return strings.Join(s, " ")
 	}
-	return strings.Join(s, " ")
+	return ""
 }
 
 func getRingZeroGatewayID(z *Zone) int {