diff --git a/src/geovista/bridge.py b/src/geovista/bridge.py
index 1da2938f..990a4a84 100644
--- a/src/geovista/bridge.py
+++ b/src/geovista/bridge.py
@@ -880,7 +880,7 @@ def __init__(
         zlevel: int | None = None,
         zscale: float | None = None,
         clean: bool | None = None,
-    ):
+    ) -> None:
         """Build a mesh from spatial points, connectivity, data and CRS metadata.
 
         Convenience factory to build multiple identical meshes but with different face
diff --git a/src/geovista/core.py b/src/geovista/core.py
index 98eaeaeb..c87b3336 100644
--- a/src/geovista/core.py
+++ b/src/geovista/core.py
@@ -88,7 +88,7 @@ def __init__(
         mesh: pv.PolyData,
         meridian: float,
         offset: float | None = None,
-    ):
+    ) -> None:
         """Create a `meridian` seam in the `mesh`.
 
         The seam extends from the north-pole to the south-pole in a great circle,
diff --git a/src/geovista/geodesic.py b/src/geovista/geodesic.py
index 62b0665c..07149635 100644
--- a/src/geovista/geodesic.py
+++ b/src/geovista/geodesic.py
@@ -122,7 +122,7 @@ def __init__(
         ellps: str | None = ELLIPSE,
         c: int | None = BBOX_C,
         triangulate: bool | None = False,
-    ):
+    ) -> None:
         """Create 3-D geodesic bounding-box to extract enclosed mesh, lines or point.
 
         The bounding-box region is specified in terms of its four corners, in
diff --git a/src/geovista/geoplotter.py b/src/geovista/geoplotter.py
index b6d0d24b..1d6c3a1d 100644
--- a/src/geovista/geoplotter.py
+++ b/src/geovista/geoplotter.py
@@ -116,7 +116,7 @@ class GeoPlotterBase:
 
     """
 
-    def __init__(self, *args: Any | None, **kwargs: Any | None):
+    def __init__(self, *args: Any | None, **kwargs: Any | None) -> None:
         """Create geospatial aware plotter.
 
         Parameters
diff --git a/src/geovista/search.py b/src/geovista/search.py
index ad3d222f..fe776fc2 100644
--- a/src/geovista/search.py
+++ b/src/geovista/search.py
@@ -70,7 +70,7 @@ def __init__(
         mesh: PolyData,
         leaf_size: int | None = None,
         preference: str | Preference | None = None,
-    ):
+    ) -> None:
         """Construct kd-tree for nearest neighbour search of mesh points/cell centers.
 
         Note that, the cell centers will be calculated from the mesh geometry and do not