diff --git a/client.go b/client.go
index 36a074b..74f24ad 100644
--- a/client.go
+++ b/client.go
@@ -19,6 +19,9 @@ import (
 
 const CausalityTokenHeader = "X-Garage-Causality-Token"
 
+const payloadHashEmpty = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
+const payloadHashUnsigned = "UNSIGNED-PAYLOAD"
+
 var TombstoneItemErr = errors.New("item is a tombstone")
 var NoSuchItemErr = errors.New("item does not exist")
 var ConcurrentItemsErr = errors.New("item has multiple concurrent values")
@@ -95,7 +98,7 @@ func (c *Client) executeRequest(req *http.Request) (*http.Response, error) {
 		return nil, err
 	}
 
-	resp, err := http.DefaultClient.Do(req)
+	resp, err := c.httpClient.Do(req)
 	if err != nil {
 		return nil, err
 	}
@@ -104,14 +107,25 @@ func (c *Client) executeRequest(req *http.Request) (*http.Response, error) {
 }
 
 func (c *Client) signRequest(req *http.Request) error {
+	if c.key.ID == "" || c.key.Secret == "" {
+		return errors.New("no credentials provided")
+	}
+
 	creds := aws.Credentials{
 		AccessKeyID:     c.key.ID,
 		SecretAccessKey: c.key.Secret,
 	}
-	const noBody = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
-	req.Header.Set("X-Amz-Content-Sha256", noBody)
 
-	err := awsSigner.SignHTTP(req.Context(), creds, req, noBody, "k2v", "garage", time.Now())
+	var payloadHash string
+	if req.Body == nil || req.Body == http.NoBody {
+
+		payloadHash = payloadHashEmpty
+	} else {
+		payloadHash = payloadHashUnsigned
+	}
+	req.Header.Set("X-Amz-Content-Sha256", payloadHash)
+
+	err := awsSigner.SignHTTP(req.Context(), creds, req, payloadHash, "k2v", "garage", time.Now())
 	if err != nil {
 		return err
 	}
@@ -248,9 +262,6 @@ func (c *Client) ReadItemMulti(ctx context.Context, b Bucket, pk string, sk stri
 		return []Item{body}, ct, nil
 	case "application/json":
 		var items []Item
-		if err != nil {
-			return nil, "", err
-		}
 		if err := json.Unmarshal(body, &items); err != nil {
 			return nil, "", err
 		}
diff --git a/client_test.go b/client_test.go
index 2aa0605..d7feaf1 100644
--- a/client_test.go
+++ b/client_test.go
@@ -27,7 +27,7 @@ func newFixture(t testing.TB) (*fixture, context.Context) {
 		t:      t,
 		ctx:    ctx,
 		cli:    cli,
-		bucket: k2v.Bucket("k2v-test"),
+		bucket: TestBucket,
 	}
 
 	return f, ctx
diff --git a/main_test.go b/main_test.go
index c5a3d85..65554a0 100644
--- a/main_test.go
+++ b/main_test.go
@@ -1,10 +1,16 @@
-package k2v
+package k2v_test
 
 import (
+	k2v "code.notaphish.fyi/milas/garage-k2v-go"
 	"go.uber.org/goleak"
+	"os"
 	"testing"
 )
 
+const BucketEnvVar = "K2V_TEST_BUCKET"
+
+var TestBucket = k2v.Bucket(os.Getenv(BucketEnvVar))
+
 func TestMain(m *testing.M) {
 	goleak.VerifyTestMain(m)
 }
diff --git a/pager_test.go b/pager_test.go
index 5d5a661..6ed8cd6 100644
--- a/pager_test.go
+++ b/pager_test.go
@@ -32,15 +32,14 @@ func ExampleScrollIndex() {
 	ctx := context.Background()
 	client := k2v.NewClient(k2v.EndpointFromEnv(), k2v.KeyFromEnv())
 	defer client.Close()
-	const bucket = "k2v-test"
 
 	pkPrefix := randomPk()
 	for i := range 5 {
-		_ = client.InsertItem(ctx, bucket, pkPrefix+"-"+strconv.Itoa(i), randomSk(), "", []byte("hello"))
+		_ = client.InsertItem(ctx, TestBucket, pkPrefix+"-"+strconv.Itoa(i), randomSk(), "", []byte("hello"))
 	}
 
 	var responses []*k2v.ReadIndexResponse
-	_ = k2v.ScrollIndex(ctx, client, bucket, k2v.ReadIndexQuery{Prefix: pkPrefix, Limit: 25}, func(resp *k2v.ReadIndexResponse) error {
+	_ = k2v.ScrollIndex(ctx, client, TestBucket, k2v.ReadIndexQuery{Prefix: pkPrefix, Limit: 25}, func(resp *k2v.ReadIndexResponse) error {
 		responses = append(responses, resp)
 		return nil
 	})
diff --git a/poll_batch_test.go b/poll_batch_test.go
index 384aafa..c0c91cd 100644
--- a/poll_batch_test.go
+++ b/poll_batch_test.go
@@ -114,4 +114,5 @@ func TestClient_PollRange_Timeout(t *testing.T) {
 	q.SeenMarker = result.SeenMarker
 	result, err = f.cli.PollRange(ctx, f.bucket, pk, q, 1*time.Second)
 	require.ErrorIs(t, err, k2v.NotModifiedTimeoutErr)
+	require.Nil(t, result)
 }
diff --git a/poll_single_test.go b/poll_single_test.go
index dcca3de..d65521e 100644
--- a/poll_single_test.go
+++ b/poll_single_test.go
@@ -20,6 +20,7 @@ func TestClient_PollItem(t *testing.T) {
 	require.NoError(t, err)
 
 	_, ct, err := f.cli.ReadItemSingle(ctx, f.bucket, pk, sk)
+	require.NoError(t, err)
 
 	updateErrCh := make(chan error, 1)
 	pollReadyCh := make(chan struct{})
@@ -63,7 +64,9 @@ func TestClient_PollItem_Timeout(t *testing.T) {
 	require.NoError(t, err)
 
 	_, ct, err := f.cli.ReadItemSingle(ctx, f.bucket, pk, sk)
-	item, ct, err := f.cli.PollItem(ctx, f.bucket, pk, sk, ct, 1*time.Second)
+	require.NoError(t, err)
+
+	item, _, err := f.cli.PollItem(ctx, f.bucket, pk, sk, ct, 1*time.Second)
 	require.ErrorIs(t, err, k2v.NotModifiedTimeoutErr)
 	require.Empty(t, item)
 }
diff --git a/read_batch.go b/read_batch.go
index 2ff045c..e4382a5 100644
--- a/read_batch.go
+++ b/read_batch.go
@@ -54,9 +54,9 @@ type BatchSearchResult struct {
 }
 
 type SearchResultItem struct {
-	SortKey        string `json:"sk"`
-	CausalityToken string `json:"ct"`
-	Values         []Item `json:"v"`
+	SortKey        string         `json:"sk"`
+	CausalityToken CausalityToken `json:"ct"`
+	Values         []Item         `json:"v"`
 }
 
 func (c *Client) ReadBatch(ctx context.Context, b Bucket, q []BatchSearch) ([]*BatchSearchResult, error) {