diff --git a/Dockerfile b/Dockerfile
index 03a064bd63..2cffa6bbed 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 # Build the manager binary
-FROM golang:1.20.10 as builder
+FROM golang:1.21.6 as builder
 WORKDIR /workspace
 
 # Run this with docker build --build_arg goproxy=$(go env GOPROXY) to override the goproxy
diff --git a/pkg/cloud/services/loadbalancer/loadbalancer.go b/pkg/cloud/services/loadbalancer/loadbalancer.go
index 75e2201779..00730d673e 100644
--- a/pkg/cloud/services/loadbalancer/loadbalancer.go
+++ b/pkg/cloud/services/loadbalancer/loadbalancer.go
@@ -19,7 +19,7 @@ package loadbalancer
 import (
 	"errors"
 	"fmt"
-	"reflect"
+	"slices"
 	"time"
 
 	"github.com/gophercloud/gophercloud/openstack/loadbalancer/v2/listeners"
@@ -275,11 +275,11 @@ func (s *Service) getOrUpdateAllowedCIDRS(openStackCluster *infrav1.OpenStackClu
 	// Validate CIDRs and convert any given IP into a CIDR.
 	allowedCIDRs = validateIPs(openStackCluster, allowedCIDRs)
 
-	// Remove duplicates.
-	allowedCIDRs = capostrings.Unique(allowedCIDRs)
-	listener.AllowedCIDRs = capostrings.Unique(listener.AllowedCIDRs)
+	// Sort and remove duplicates
+	allowedCIDRs = capostrings.Canonicalize(allowedCIDRs)
+	listener.AllowedCIDRs = capostrings.Canonicalize(listener.AllowedCIDRs)
 
-	if !reflect.DeepEqual(allowedCIDRs, listener.AllowedCIDRs) {
+	if !slices.Equal(allowedCIDRs, listener.AllowedCIDRs) {
 		s.scope.Logger().Info("CIDRs do not match, updating listener", "expectedCIDRs", allowedCIDRs, "currentCIDRs", listener.AllowedCIDRs)
 		listenerUpdateOpts := listeners.UpdateOpts{
 			AllowedCIDRs: &allowedCIDRs,
diff --git a/pkg/utils/strings/strings.go b/pkg/utils/strings/strings.go
index 6db532e1d8..ec97911fe2 100644
--- a/pkg/utils/strings/strings.go
+++ b/pkg/utils/strings/strings.go
@@ -16,14 +16,12 @@ limitations under the License.
 
 package strings
 
-func Unique(s []string) []string {
-	inResult := make(map[string]bool)
-	var result []string
-	for _, str := range s {
-		if _, ok := inResult[str]; !ok {
-			inResult[str] = true
-			result = append(result, str)
-		}
-	}
-	return result
+import (
+	"cmp"
+	"slices"
+)
+
+func Canonicalize[S ~[]E, E cmp.Ordered](s S) S {
+	slices.Sort(s)
+	return slices.Compact(s)
 }
diff --git a/pkg/utils/strings/strings_test.go b/pkg/utils/strings/strings_test.go
new file mode 100644
index 0000000000..7502f060ad
--- /dev/null
+++ b/pkg/utils/strings/strings_test.go
@@ -0,0 +1,60 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package strings
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestCanonicalize(t *testing.T) {
+	tests := []struct {
+		name  string
+		value []string
+		want  []string
+	}{
+		{
+			name:  "Empty list",
+			value: []string{},
+			want:  []string{},
+		},
+		{
+			name:  "Identity",
+			value: []string{"a", "b", "c"},
+			want:  []string{"a", "b", "c"},
+		},
+		{
+			name:  "Out of order",
+			value: []string{"c", "b", "a"},
+			want:  []string{"a", "b", "c"},
+		},
+		{
+			name:  "Duplicate elements",
+			value: []string{"c", "b", "a", "c"},
+			want:  []string{"a", "b", "c"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := Canonicalize(tt.value)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("CompareLists() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}