diff --git a/Makefile b/Makefile
index 6662a16..04a69cb 100644
--- a/Makefile
+++ b/Makefile
@@ -20,5 +20,5 @@ release:
 .PHONY: \
 	release \
 	test \
-  test-package \
-  test-examples
+	test-package \
+	test-examples
diff --git a/transloadit.go b/transloadit.go
index 5e25700..acdb038 100755
--- a/transloadit.go
+++ b/transloadit.go
@@ -293,7 +293,7 @@ func (client *Client) CreateSignedSmartCDNUrl(opts SignedSmartCDNUrlOptions) str
 
 	stringToSign := fmt.Sprintf("%s/%s/%s?%s", workspaceSlug, templateSlug, inputField, queryString)
 
-	// Create signature using SHA-256
+	// Smart CDN signatures intentionally remain SHA-256; API request signatures use SHA-384.
 	hash := hmac.New(sha256.New, []byte(client.config.AuthSecret))
 	hash.Write([]byte(stringToSign))
 	signature := url.QueryEscape("sha256:" + hex.EncodeToString(hash.Sum(nil)))
diff --git a/transloadit_signature_test.go b/transloadit_signature_test.go
new file mode 100644
index 0000000..70f5eaa
--- /dev/null
+++ b/transloadit_signature_test.go
@@ -0,0 +1,97 @@
+package transloadit
+
+import (
+	"context"
+	"crypto/hmac"
+	"crypto/sha512"
+	"encoding/hex"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestSign_UsesSha384WithAlgorithmPrefix(t *testing.T) {
+	client := NewClient(Config{
+		AuthKey:    "foo_key",
+		AuthSecret: "foo_secret",
+		Endpoint:   "https://api2.transloadit.com",
+	})
+
+	params, signature, err := client.sign(map[string]interface{}{
+		"foo": "bar",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !strings.HasPrefix(signature, "sha384:") {
+		t.Fatalf("signature prefix should be sha384:, got %q", signature)
+	}
+
+	hash := hmac.New(sha512.New384, []byte(client.config.AuthSecret))
+	hash.Write([]byte(params))
+	expected := "sha384:" + hex.EncodeToString(hash.Sum(nil))
+
+	if signature != expected {
+		t.Fatalf("wrong signature, expected %q got %q", expected, signature)
+	}
+}
+
+func TestListRequest_UsesSha384WithAlgorithmPrefix(t *testing.T) {
+	client := NewClient(Config{
+		AuthKey:    "foo_key",
+		AuthSecret: "foo_secret",
+	})
+
+	errCh := make(chan error, 1)
+	reportErr := func(err error) {
+		select {
+		case errCh <- err:
+		default:
+		}
+	}
+
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		params := r.URL.Query().Get("params")
+		signature := r.URL.Query().Get("signature")
+
+		if params == "" {
+			reportErr(fmt.Errorf("params query should be set"))
+		}
+
+		if !strings.HasPrefix(signature, "sha384:") {
+			reportErr(fmt.Errorf("listRequest signature prefix should be sha384:, got %q", signature))
+		}
+
+		hash := hmac.New(sha512.New384, []byte(client.config.AuthSecret))
+		hash.Write([]byte(params))
+		expected := "sha384:" + hex.EncodeToString(hash.Sum(nil))
+
+		if signature != expected {
+			reportErr(fmt.Errorf("wrong listRequest signature, expected %q got %q", expected, signature))
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"items":[],"count":0}`))
+	}))
+	defer server.Close()
+
+	client.config.Endpoint = server.URL
+
+	list, err := client.ListTemplates(context.Background(), &ListOptions{PageSize: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if list.Count != 0 {
+		t.Fatalf("expected empty list count 0, got %d", list.Count)
+	}
+
+	select {
+	case verifyErr := <-errCh:
+		t.Fatal(verifyErr)
+	default:
+	}
+}