diff --git a/cmd/util/cmd.go b/cmd/util/cmd.go
index 16cc22f1a9..ec72cfceac 100644
--- a/cmd/util/cmd.go
+++ b/cmd/util/cmd.go
@@ -18,6 +18,7 @@ package cmdutil
 
 import (
 	"fmt"
+	"slices"
 	"strings"
 )
 
@@ -49,12 +50,10 @@ func (c *CobraStringValue) IsSet() bool { return c.isSet }
 
 // Set sets a value and fails if it is not allowed
 func (c *CobraStringValue) Set(other string) error {
-	for _, s := range c.allowed {
-		if other == s {
-			c.value = other
-			c.isSet = true
-			return nil
-		}
+	if slices.Contains(c.allowed, other) {
+		c.value = other
+		c.isSet = true
+		return nil
 	}
 	return fmt.Errorf("value %s not allowed", other)
 }
diff --git a/network/phonebook/phonebook_test.go b/network/phonebook/phonebook_test.go
index b0805582d0..b07b8f2f7d 100644
--- a/network/phonebook/phonebook_test.go
+++ b/network/phonebook/phonebook_test.go
@@ -17,6 +17,7 @@
 package phonebook
 
 import (
+	"slices"
 	"testing"
 	"time"
 
@@ -27,25 +28,13 @@ import (
 func testPhonebookAll(t *testing.T, set []string, ph Phonebook) {
 	actual := ph.GetAddresses(len(set), RelayRole)
 	for _, got := range actual {
-		ok := false
-		for _, known := range set {
-			if got == known {
-				ok = true
-				break
-			}
-		}
+		ok := slices.Contains(set, got)
 		if !ok {
 			t.Errorf("get returned junk %#v", got)
 		}
 	}
 	for _, known := range set {
-		ok := false
-		for _, got := range actual {
-			if got == known {
-				ok = true
-				break
-			}
-		}
+		ok := slices.Contains(actual, known)
 		if !ok {
 			t.Errorf("get missed %#v; actual=%#v; set=%#v", known, actual, set)
 		}