diff --git a/src/affinder/_tests/test_affinder.py b/src/affinder/_tests/test_affinder.py
index 16fbf92..a7441d1 100644
--- a/src/affinder/_tests/test_affinder.py
+++ b/src/affinder/_tests/test_affinder.py
@@ -66,7 +66,7 @@ def test_2d_2d(make_napari_viewer, tmp_path, reference, moving, model_class):
     l0.name = "layer0"
 
     l1 = viewer.add_layer(moving)
-    l1.name = "layer1"
+    l1.name = 'layer1'
 
     affinder_widget = start_affinder()
     affinder_widget(
diff --git a/src/affinder/affinder.py b/src/affinder/affinder.py
index 6a754f8..8b51026 100644
--- a/src/affinder/affinder.py
+++ b/src/affinder/affinder.py
@@ -159,7 +159,10 @@ def _on_affinder_main_init(widget):
         widget_init=_on_affinder_main_init,
         call_button='Start',
         layout='vertical',
-        output={'mode': 'w'},
+        output={
+                'mode': 'w', 'label': 'Save transformation as', 'filter':
+                        '*.txt'
+                },
         viewer={'visible': False, 'label': ' '},
         delete_pts={
                 'label':