diff --git a/lidro/merge_mask_hydro/vectors/close_holes.py b/lidro/merge_mask_hydro/vectors/close_holes.py
index 3eb3f57b..cec8047c 100644
--- a/lidro/merge_mask_hydro/vectors/close_holes.py
+++ b/lidro/merge_mask_hydro/vectors/close_holes.py
@@ -20,7 +20,7 @@ def close_holes(polygon, min_hole_area):
     # Create polygons from each exterior contour without holes
     exterior_polygons = [Polygon(ring) for ring in exterior_contours]
     # Merge all polygons into a single encompassing shape
-    unified_shape = unary_union(polygons)
+    unified_shape = unary_union(exterior_polygons)
 
     # Interior Hydro Mask
     interiors_to_keep = [
diff --git a/test/vectors/test_merge_vector.py b/test/vectors/test_merge_vector.py
index 7facd361..5f160cf5 100644
--- a/test/vectors/test_merge_vector.py
+++ b/test/vectors/test_merge_vector.py
@@ -37,5 +37,5 @@ def test_create_hydro_vector_mask_default():
     assert gdf.crs.to_string() == crs  # CRS is identical
     assert all(isinstance(geom, Polygon) for geom in gdf.geometry)  # All geometry should Polygons
 
-    expected_number_of_geometries = 1
+    expected_number_of_geometries = 3
     assert len(gdf) == expected_number_of_geometries  # One geometry