diff --git a/dataflow/dataflow_test.go b/dataflow/dataflow_test.go
index 3802ff2..d6bae85 100644
--- a/dataflow/dataflow_test.go
+++ b/dataflow/dataflow_test.go
@@ -125,7 +125,7 @@ func TestDataflow_Xml(t *testing.T) {
 func TestDataflow_Multipart(t *testing.T) {
 	df := InitBaseDataflow()
 
-	df.Multipart(func(multipart MultipartDataflow) {
+	df.Multipart(func(multipart MultipartDataflow) error {
 		mpDataflow := NewMultipartHelper()
 		mpDataflow.Boundary("test-boundary")
 		mpDataflow.FieldValue("param1", "value1")
@@ -134,6 +134,7 @@ func TestDataflow_Multipart(t *testing.T) {
 		if mpDataflow.Err() != nil {
 			t.Error(mpDataflow.Err())
 		}
+		return nil
 	})
 
 	if df.Err() != nil {
diff --git a/dataflow/multipart.go b/dataflow/multipart.go
index 383ef00..2e21923 100644
--- a/dataflow/multipart.go
+++ b/dataflow/multipart.go
@@ -39,15 +39,7 @@ func (m *MultipartDf) FileByPath(fieldName string, filePath string) MultipartDat
 	_, fileName := path.Split(filePath)
 
 	writer, err := m.mWriter.CreateFormFile(fieldName, fileName)
-	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
-	}
-	var buf bytes.Buffer
-	_, err = buf.ReadFrom(file)
-	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
-	}
-	_, err = buf.WriteTo(writer)
+	_, err = io.Copy(writer, file)
 	if err != nil {
 		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
 	}
@@ -59,12 +51,7 @@ func (m *MultipartDf) FileMem(fieldName string, fileName string, reader io.Reade
 	if err != nil {
 		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
 	}
-	var buf bytes.Buffer
-	_, err = buf.ReadFrom(reader)
-	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
-	}
-	_, err = buf.WriteTo(writer)
+	_, err = io.Copy(writer, reader)
 	if err != nil {
 		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
 	}
@@ -77,16 +64,9 @@ func (m *MultipartDf) Part(header textproto.MIMEHeader, reader io.Reader) Multip
 		m.errs = append(m.errs, errors.Wrap(err, "create part failed"))
 		return m
 	}
-	var buf bytes.Buffer
-	_, err = buf.ReadFrom(reader)
+	_, err = io.Copy(writer, reader)
 	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create part read failed"))
-		return m
-	}
-	_, err = buf.WriteTo(writer)
-	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create part write failed"))
-		return m
+		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
 	}
 	return m
 }
@@ -105,16 +85,9 @@ func (m *MultipartDf) Field(fieldName string, reader io.Reader) MultipartDataflo
 		m.errs = append(m.errs, errors.Wrap(err, "create field failed"))
 		return m
 	}
-	var buf bytes.Buffer
-	_, err = buf.ReadFrom(reader)
+	_, err = io.Copy(writer, reader)
 	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create field read failed"))
-		return m
-	}
-	_, err = buf.WriteTo(writer)
-	if err != nil {
-		m.errs = append(m.errs, errors.Wrap(err, "create field write failed"))
-		return m
+		m.errs = append(m.errs, errors.Wrap(err, "create file part failed"))
 	}
 	return m
 }
diff --git a/example_test.go b/example_test.go
index e24bbcd..0ca6020 100644
--- a/example_test.go
+++ b/example_test.go
@@ -161,13 +161,14 @@ func TestRequestHelper_Df_Multipart(t *testing.T) {
 
 	_, err = helper.Df().Method(http.MethodPost).
 		Url("https://typedwebhook.tools/webhook").
-		Multipart(func(multipart dataflow.MultipartDataflow) {
+		Multipart(func(multipart dataflow.MultipartDataflow) error {
 			data := strings.NewReader("test data")
 			multipart.Boundary("test-boundary").
 				//FileByPath("file", "README.md").
 				FieldValue("param1", "value1").
 				FieldValue("param2", "value2").
 				Field("data", data)
+			return nil
 		}).Request()
 
 	if err != nil {