diff --git a/brainreg/napari/register.py b/brainreg/napari/register.py
index 0b59ca8..fd70780 100644
--- a/brainreg/napari/register.py
+++ b/brainreg/napari/register.py
@@ -560,11 +560,11 @@ def check_orientation(event=None):
         atlas = BrainGlobeAtlas(widget.atlas_key.value.name)
         if brain_geometry.value == "hemisphere_l":
             atlas.reference[
-                atlas.hemispheres == atlas.left_hemisphere_value
+                atlas.hemispheres == atlas.right_hemisphere_value
             ] = 0
         elif brain_geometry.value == "hemisphere_r":
             atlas.reference[
-                atlas.hemispheres == atlas.right_hemisphere_value
+                atlas.hemispheres == atlas.left_hemisphere_value
             ] = 0
         input_orientation = getattr(widget, "data_orientation").value
         data = getattr(widget, "img_layer").value.data