diff --git a/cf_xarray/geometry.py b/cf_xarray/geometry.py
index 40fa1743..26c12293 100644
--- a/cf_xarray/geometry.py
+++ b/cf_xarray/geometry.py
@@ -440,7 +440,7 @@ def cf_to_lines(ds: xr.Dataset):
     return xr.DataArray(geoms, dims=part_node_count.dims, coords=part_node_count.coords)
 
 
-  def grid_to_polygons(ds: xr.Dataset) -> xr.DataArray:
+def grid_to_polygons(ds: xr.Dataset) -> xr.DataArray:
     """
     Converts a regular 2D lat/lon grid to a 2D array of shapely polygons.