diff --git a/files/filestore.go b/files/filestore.go
index fdf1978..5ed0ddc 100644
--- a/files/filestore.go
+++ b/files/filestore.go
@@ -12,6 +12,8 @@ type File struct {
 	ExpiresOn        time.Time `json:"expires_on"`
 
 	Body io.ReadCloser
+
+	FileSize int64 `json:"file_size"`
 }
 
 type FileStore interface {
diff --git a/files/filestore_fs.go b/files/filestore_fs.go
index ce19995..5bf6e6c 100644
--- a/files/filestore_fs.go
+++ b/files/filestore_fs.go
@@ -40,10 +40,12 @@ func (s *FSFileStore) Store(f *File) error {
 	}
 	defer dst.Close()
 
-	if _, err := io.Copy(dst, f.Body); err != nil {
+	n, err := io.Copy(dst, f.Body)
+	if err != nil {
 		return err
 	}
 	s.metadata[f.ID] = metadata
+	s.metadata[f.ID].FileSize = n
 	if err := s.writeMetadata(); err != nil {
 		delete(s.metadata, f.ID)
 		return err
diff --git a/files/filestore_memory.go b/files/filestore_memory.go
index 0dd7e76..0640c90 100644
--- a/files/filestore_memory.go
+++ b/files/filestore_memory.go
@@ -14,6 +14,7 @@ type fileData struct {
 
 	MaxViews  uint
 	ExpiresOn time.Time
+	FileSize  int64
 }
 
 type MemoryFileStore struct {
@@ -35,9 +36,11 @@ func (s *MemoryFileStore) Store(f *File) error {
 		ExpiresOn: f.ExpiresOn,
 	}
 
-	_, err := io.Copy(&data.Body, f.Body)
+	n, err := io.Copy(&data.Body, f.Body)
 	_ = f.Body.Close()
 
+	data.FileSize = n
+
 	s.lock.Lock()
 	defer s.lock.Unlock()
 
diff --git a/files/filestore_test.go b/files/filestore_test.go
index 6c7c52f..a27ea91 100644
--- a/files/filestore_test.go
+++ b/files/filestore_test.go
@@ -92,6 +92,7 @@ func RunPersistentFilestoreTest(newStoreFunc func() files.FileStore, t *testing.
 				MaxViews:         5,
 				ExpiresOn:        time.Now().Add(10 * time.Minute),
 				Body:             io.NopCloser(strings.NewReader("cocks!")),
+				FileSize:         6,
 			},
 			ExpectedData: "cocks!",
 		},
@@ -102,6 +103,7 @@ func RunPersistentFilestoreTest(newStoreFunc func() files.FileStore, t *testing.
 				MaxViews:         5,
 				ExpiresOn:        time.Now().Add(10 * time.Minute),
 				Body:             io.NopCloser(strings.NewReader("derps!")),
+				FileSize:         6,
 			},
 			ExpectedData: "derps!",
 		},