diff --git a/cmd/kube-proxy/app/BUILD b/cmd/kube-proxy/app/BUILD
index f3d7586bc3c..081ac969874 100644
--- a/cmd/kube-proxy/app/BUILD
+++ b/cmd/kube-proxy/app/BUILD
@@ -167,6 +167,7 @@ go_test(
         "//pkg/proxy/apis/config:go_default_library",
         "//pkg/util/configz:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
         "//staging/src/k8s.io/apimachinery/pkg/util/diff:go_default_library",
         "//staging/src/k8s.io/component-base/config:go_default_library",
         "//vendor/github.com/stretchr/testify/assert:go_default_library",
diff --git a/cmd/kube-proxy/app/server_test.go b/cmd/kube-proxy/app/server_test.go
index 0fc014e9308..e32fb23b1ca 100644
--- a/cmd/kube-proxy/app/server_test.go
+++ b/cmd/kube-proxy/app/server_test.go
@@ -30,12 +30,14 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
+	utilpointer "k8s.io/utils/pointer"
+
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	kuberuntime "k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/diff"
 	componentbaseconfig "k8s.io/component-base/config"
 	kubeproxyconfig "k8s.io/kubernetes/pkg/proxy/apis/config"
 	"k8s.io/kubernetes/pkg/util/configz"
-	utilpointer "k8s.io/utils/pointer"
 )
 
 // This test verifies that NewProxyServer does not crash when CleanupAndExit is true.
@@ -279,10 +281,16 @@ nodePortAddresses:
 
 // TestLoadConfigFailures tests failure modes for loadConfig()
 func TestLoadConfigFailures(t *testing.T) {
+	yamlTemplate := `bindAddress: 0.0.0.0
+clusterCIDR: "1.2.3.0/24"
+configSyncPeriod: 15s
+kind: KubeProxyConfiguration`
+
 	testCases := []struct {
-		name   string
-		config string
-		expErr string
+		name    string
+		config  string
+		expErr  string
+		checkFn func(err error) bool
 	}{
 		{
 			name:   "Decode error test",
@@ -299,15 +307,34 @@ func TestLoadConfigFailures(t *testing.T) {
 			config: "bindAddress: ::",
 			expErr: "mapping values are not allowed in this context",
 		},
+		{
+			name:    "Duplicate fields",
+			config:  fmt.Sprintf("%s\nbindAddess: 1.2.3.4", yamlTemplate),
+			checkFn: kuberuntime.IsStrictDecodingError,
+		},
+		{
+			name:    "Unknown field",
+			config:  fmt.Sprintf("%s\nfoo: bar", yamlTemplate),
+			checkFn: kuberuntime.IsStrictDecodingError,
+		},
 	}
+
 	version := "apiVersion: kubeproxy.config.k8s.io/v1alpha1"
 	for _, tc := range testCases {
-		options := NewOptions()
-		config := fmt.Sprintf("%s\n%s", version, tc.config)
-		_, err := options.loadConfig([]byte(config))
-		if assert.Error(t, err, tc.name) {
-			assert.Contains(t, err.Error(), tc.expErr, tc.name)
-		}
+		t.Run(tc.name, func(t *testing.T) {
+			options := NewOptions()
+			config := fmt.Sprintf("%s\n%s", version, tc.config)
+			_, err := options.loadConfig([]byte(config))
+
+			if assert.Error(t, err, tc.name) {
+				if tc.expErr != "" {
+					assert.Contains(t, err.Error(), tc.expErr)
+				}
+				if tc.checkFn != nil {
+					assert.True(t, tc.checkFn(err), tc.name)
+				}
+			}
+		})
 	}
 }
 
diff --git a/pkg/proxy/apis/config/scheme/scheme.go b/pkg/proxy/apis/config/scheme/scheme.go
index e2f408bd8ac..75e8082b25e 100644
--- a/pkg/proxy/apis/config/scheme/scheme.go
+++ b/pkg/proxy/apis/config/scheme/scheme.go
@@ -29,7 +29,7 @@ var (
 	Scheme = runtime.NewScheme()
 	// Codecs provides methods for retrieving codecs and serializers for specific
 	// versions and content types.
-	Codecs = serializer.NewCodecFactory(Scheme)
+	Codecs = serializer.NewCodecFactory(Scheme, serializer.EnableStrict)
 )
 
 func init() {