diff --git a/pkg/kube/client_test.go b/pkg/kube/client_test.go
index de5358aee..a7c20473e 100644
--- a/pkg/kube/client_test.go
+++ b/pkg/kube/client_test.go
@@ -21,9 +21,11 @@ import (
 	"io"
 	"io/ioutil"
 	"net/http"
+	"os"
 	"strings"
 	"testing"
 
+	"helm.sh/helm/v3/pkg/cli"
 	v1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -253,6 +255,84 @@ func TestBuild(t *testing.T) {
 	}
 }
 
+func TestNamespace(t *testing.T) {
+	reset := func() func() {
+		var originalHelmNamespace *string
+		origEnv := os.Environ()
+		for _, pair := range origEnv {
+			kv := strings.SplitN(pair, "=", 2)
+			if kv[0] == "HELM_NAMESPACE" {
+				o := kv[1]
+				originalHelmNamespace = &o
+				break
+			}
+		}
+
+		return func() {
+			os.Unsetenv("HELM_NAMESPACE")
+			if originalHelmNamespace != nil {
+				os.Setenv("HELM_NAMESPACE", *originalHelmNamespace)
+			}
+		}
+	}
+
+	refstring := func(s string) *string {
+		return &s
+	}
+	tcs := []struct {
+		name              string
+		envNamespace      string
+		namespace         *string
+		expectedNamespace string
+	}{
+		{
+			name:              "unset-namespace",
+			envNamespace:      v1.NamespaceDefault,
+			namespace:         nil,
+			expectedNamespace: v1.NamespaceDefault,
+		}, {
+			name:              "test-namespace",
+			envNamespace:      v1.NamespaceDefault,
+			namespace:         refstring("test"),
+			expectedNamespace: "test",
+		}, {
+			name:              "non-default-env-namespace",
+			envNamespace:      "test",
+			namespace:         nil,
+			expectedNamespace: "test",
+		}, {
+			name:              "non-default-env-and-test-namespace",
+			envNamespace:      "stage",
+			namespace:         refstring("test"),
+			expectedNamespace: "test",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			defer reset()()
+
+			os.Setenv("HELM_NAMESPACE", tc.envNamespace)
+			c := New(cli.New().RESTClientGetter())
+			if tc.namespace != nil {
+				c.Namespace = *tc.namespace
+			}
+			reslist, err := c.Build(strings.NewReader(testServiceManifest), true)
+			if err != nil {
+				t.Errorf("unexpected error from Build: %v", err)
+			}
+			if len(reslist) != 1 {
+				t.Errorf("expected 1 resource; got %d", len(reslist))
+			}
+			res := reslist[0]
+			t.Logf("%#v\n", res)
+			if res.Namespace != tc.expectedNamespace {
+				t.Errorf("Incorrect namespace: expected '%s', got '%s'", tc.expectedNamespace, res.Namespace)
+			}
+		})
+	}
+}
+
 func TestPerform(t *testing.T) {
 	tests := []struct {
 		name       string