diff --git a/droplets/image_analysis.py b/droplets/image_analysis.py
index 230207d..e8f1165 100644
--- a/droplets/image_analysis.py
+++ b/droplets/image_analysis.py
@@ -590,7 +590,7 @@ def refine_droplet(
             least_squares_params.setdefault(key, tolerance)
 
     if not isinstance(droplet, DiffuseDroplet):
-        droplet_obj = DiffuseDroplet.from_droplet(droplet)
+        droplet = DiffuseDroplet.from_droplet(droplet)
     if droplet.interface_width is None:
         droplet.interface_width = phase_field.grid.typical_discretization