diff --git a/web/file2/fs.go b/web/file2/fs.go
index aeb0370..db4f676 100644
--- a/web/file2/fs.go
+++ b/web/file2/fs.go
@@ -54,9 +54,13 @@ func StoreFromHTTP(fs FS, r *http.Request, key string) error {
 	buf := make([]byte, 512)
 	n, err := file.Read(buf)
 	if err != nil && err != io.EOF {
-		return err
+		return fmt.Errorf("read from file: %w", err)
 	}
 	contentType := http.DetectContentType(buf[:n])
+	_, err = file.Seek(0, io.SeekStart)
+	if err != nil {
+		return fmt.Errorf("seek in file: %w", err)
+	}
 
 	i := strings.LastIndexAny(fileHeader.Filename, "/\\")
 	// if i == -1 { i = -1 }
diff --git a/web/file2/fs_test.go b/web/file2/fs_test.go
index 852a198..98ba2f3 100644
--- a/web/file2/fs_test.go
+++ b/web/file2/fs_test.go
@@ -1,17 +1,81 @@
 package file_test
 
 import (
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
+	"mime"
+	"mime/multipart"
 	"net/http"
+	"net/http/httptest"
 	"os"
+	"testing"
 
 	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
 
 	"dev.sum7.eu/genofire/golang-lib/web/file2"
 )
 
-var fs file.FS
+type TestFS struct {
+	assert      *assert.Assertions
+	filename    string
+	data        string
+	contentType string
+}
+
+func (f TestFS) Store(id uuid.UUID, name, contentType string, data io.Reader) error {
+	f.assert.Equal(f.filename, name)
+	dat, err := io.ReadAll(data)
+	f.assert.NoError(err)
+	f.assert.Equal(f.data, string(dat))
+	contentType, _, err = mime.ParseMediaType(contentType)
+	f.assert.NoError(err)
+	f.assert.Equal(f.contentType, contentType)
+	return nil
+}
+
+func (f TestFS) RemoveUUID(id uuid.UUID) error {
+	return errors.New("TestFS.RemoveUUID called")
+}
+
+func (f TestFS) Open(name string) (fs.File, error) {
+	return nil, errors.New("TestFS.Open called")
+}
+
+func (f TestFS) OpenUUID(uuid.UUID) (fs.File, error) {
+	return nil, errors.New("TestFS.OpenUUID called")
+}
+
+func (f TestFS) Check() error { return nil }
+
+func TestStoreFromHTTP(t *testing.T) {
+	assert := assert.New(t)
+
+	testfs := TestFS{
+		assert:      assert,
+		filename:    "cute-cat.png",
+		data:        "content\nof file",
+		contentType: "text/plain",
+	}
+
+	r, w := io.Pipe()
+	m := multipart.NewWriter(w)
+	rq := httptest.NewRequest("PUT", "/", r)
+	rq.Header.Set("Content-Type", m.FormDataContentType())
+	go func() {
+		f, err := m.CreateFormFile("file", testfs.filename)
+		assert.NoError(err)
+		_, err = f.Write([]byte(testfs.data))
+		assert.NoError(err)
+		m.Close()
+	}()
+
+	assert.NoError(file.StoreFromHTTP(testfs, rq, "file"))
+}
+
+var fstore file.FS
 
 func ExampleFS() {
 	// generate the UUID for the new file
@@ -20,13 +84,13 @@ func ExampleFS() {
 	// store a file
 	{
 		f, _ := os.Open("glenda.png")
-		fs.Store(id, "glenda.png", "image/png", f)
+		fstore.Store(id, "glenda.png", "image/png", f)
 		f.Close()
 	}
 
 	// copy back to a local file
 	{
-		r, _ := fs.OpenUUID(id)
+		r, _ := fstore.OpenUUID(id)
 		w, _ := os.Create("glenda.png")
 		io.Copy(w, r)
 		r.Close()
@@ -36,7 +100,7 @@ func ExampleFS() {
 
 func ExampleStoreFromHTTP() {
 	http.HandleFunc("/upload", func(w http.ResponseWriter, r *http.Request) {
-		if err := file.StoreFromHTTP(fs, r, "file"); err != nil {
+		if err := file.StoreFromHTTP(fstore, r, "file"); err != nil {
 			w.Header().Set("content-type", "application/json")
 			w.WriteHeader(http.StatusInternalServerError)
 			w.Write([]byte(fmt.Sprintf(`{"message":"%v"}`, err)))