diff --git a/api/uploader/archive.go b/api/uploader/archive.go
index 4cbf9a3..eff92c1 100644
--- a/api/uploader/archive.go
+++ b/api/uploader/archive.go
@@ -182,7 +182,7 @@ func (u *API) DownloadBackedUpAsset(params DownloadBackedUpAssetParams) (string,
 // PrivateDownloadURLParams are the parameters for PrivateDownloadURL.
 type PrivateDownloadURLParams struct {
 	PublicID     string        `json:"public_id"`
-	Format       string        `json:"format"`
+	Format       string        `json:"format,omitempty"`
 	DeliveryType string        `json:"type,omitempty"`
 	Attachment   string        `json:"attachment,omitempty"`
 	ExpiresAt    *time.Time    `json:"expires_at,omitempty"`
diff --git a/api/uploader/archive_test.go b/api/uploader/archive_test.go
index 747477e..da5d243 100644
--- a/api/uploader/archive_test.go
+++ b/api/uploader/archive_test.go
@@ -102,6 +102,18 @@ func TestUploader_PrivateDownloadURL(t *testing.T) {
 	assert.Contains(t, privateDownloadURL, "timestamp")
 }
 
+func TestUploader_PrivateDownloadURLWithoutFormat(t *testing.T) {
+	params := uploader.PrivateDownloadURLParams{
+		PublicID: cldtest.PublicID,
+	}
+
+	privateDownloadURL, err := uploadAPI.PrivateDownloadURL(params)
+
+	assert.NoError(t, err)
+	assert.Contains(t, privateDownloadURL, "public_id="+cldtest.PublicID)
+	assert.NotContains(t, privateDownloadURL, "format=")
+}
+
 func TestUploader_ExpiresAtIsUnixTimestamp(t *testing.T) {
 	expiresAt := time.Unix(1800000000, 0).UTC()