diff --git a/cmd/kubeadm/app/phases/kubelet/config.go b/cmd/kubeadm/app/phases/kubelet/config.go
index 0d5f6c33a45..3236edb58b6 100644
--- a/cmd/kubeadm/app/phases/kubelet/config.go
+++ b/cmd/kubeadm/app/phases/kubelet/config.go
@@ -29,6 +29,7 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	clientset "k8s.io/client-go/kubernetes"
 	kubeletconfig "k8s.io/kubelet/config/v1beta1"
+	"sigs.k8s.io/yaml"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/componentconfigs"
@@ -56,20 +57,10 @@ func WriteConfigToDisk(cfg *kubeadmapi.ClusterConfiguration, kubeletDir, patches
 
 	// Apply patches to the KubeletConfiguration
 	if len(patchesDir) != 0 {
-		patchManager, err := patches.GetPatchManagerForPath(patchesDir, patches.KnownTargets(), output)
+		kubeletBytes, err = applyKubeletConfigPatches(kubeletBytes, patchesDir, output)
 		if err != nil {
-			return err
+			return errors.Wrap(err, "could not apply patches to the KubeletConfiguration")
 		}
-
-		patchTarget := &patches.PatchTarget{
-			Name:                      patches.KubeletConfiguration,
-			StrategicMergePatchObject: kubeletconfig.KubeletConfiguration{},
-			Data:                      kubeletBytes,
-		}
-		if err := patchManager.ApplyPatchesToTarget(patchTarget); err != nil {
-			return err
-		}
-		kubeletBytes = patchTarget.Data
 	}
 
 	return writeConfigBytesToDisk(kubeletBytes, kubeletDir)
@@ -172,3 +163,26 @@ func writeConfigBytesToDisk(b []byte, kubeletDir string) error {
 	}
 	return nil
 }
+
+// applyKubeletConfigPatches reads patches from a directory and applies them over the input kubeletBytes
+func applyKubeletConfigPatches(kubeletBytes []byte, patchesDir string, output io.Writer) ([]byte, error) {
+	patchManager, err := patches.GetPatchManagerForPath(patchesDir, patches.KnownTargets(), output)
+	if err != nil {
+		return nil, err
+	}
+
+	patchTarget := &patches.PatchTarget{
+		Name:                      patches.KubeletConfiguration,
+		StrategicMergePatchObject: kubeletconfig.KubeletConfiguration{},
+		Data:                      kubeletBytes,
+	}
+	if err := patchManager.ApplyPatchesToTarget(patchTarget); err != nil {
+		return nil, err
+	}
+
+	kubeletBytes, err = yaml.JSONToYAML(patchTarget.Data)
+	if err != nil {
+		return nil, err
+	}
+	return kubeletBytes, nil
+}
diff --git a/cmd/kubeadm/app/phases/kubelet/config_test.go b/cmd/kubeadm/app/phases/kubelet/config_test.go
index 00ce6acd83e..29ea72ef99d 100644
--- a/cmd/kubeadm/app/phases/kubelet/config_test.go
+++ b/cmd/kubeadm/app/phases/kubelet/config_test.go
@@ -17,6 +17,10 @@ limitations under the License.
 package kubelet
 
 import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
 	"testing"
 
 	v1 "k8s.io/api/core/v1"
@@ -72,3 +76,30 @@ func TestCreateConfigMapRBACRules(t *testing.T) {
 		t.Errorf("createConfigMapRBACRules: unexpected error %v", err)
 	}
 }
+
+func TestApplyKubeletConfigPatches(t *testing.T) {
+	var (
+		input          = []byte("bar: 0\nfoo: 0\n")
+		patch          = []byte("bar: 1\n")
+		expectedOutput = []byte("bar: 1\nfoo: 0\n")
+	)
+
+	dir, err := ioutil.TempDir("", "patches")
+	if err != nil {
+		t.Fatalf("could not create temp dir: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	if err := ioutil.WriteFile(filepath.Join(dir, "kubeletconfiguration.yaml"), patch, 0644); err != nil {
+		t.Fatalf("could not write patch file: %v", err)
+	}
+
+	output, err := applyKubeletConfigPatches(input, dir, ioutil.Discard)
+	if err != nil {
+		t.Fatalf("could not apply patch: %v", err)
+	}
+
+	if !bytes.Equal(output, expectedOutput) {
+		t.Fatalf("expected output:\n%s\ngot\n%s\n", expectedOutput, output)
+	}
+}