diff --git a/gridlock/base.py b/gridlock/base.py
index 6bd5fb8..aca9c69 100644
--- a/gridlock/base.py
+++ b/gridlock/base.py
@@ -1,8 +1,7 @@
-from typing import ClassVar, Self, Protocol
-from collections.abc import Callable, Sequence
+from typing import Protocol
 
 import numpy
-from numpy.typing import NDArray, ArrayLike
+from numpy.typing import NDArray
 
 from . import GridError
 
@@ -38,7 +37,7 @@ class GridBase(Protocol):
         return [self.exyz[a][:-1] + self.dxyz[a] / 2.0 for a in range(3)]
 
     @property
-    def shape(self) -> NDArray[numpy.int_]:
+    def shape(self) -> NDArray[numpy.intp]:
         """
         The number of cells in x, y, and z
 
@@ -55,7 +54,7 @@ class GridBase(Protocol):
         return self.shifts.shape[0]
 
     @property
-    def cell_data_shape(self):
+    def cell_data_shape(self) -> NDArray[numpy.intp]:
         """
         The shape of the cell_data ndarray (num_grids, *self.shape).
         """
@@ -180,7 +179,7 @@ class GridBase(Protocol):
             raise GridError('Autoshifting requires exactly 3 grids')
         return [self.shifted_dxyz(which_shifts=a)[a] for a in range(3)]
 
-    def allocate(self, fill_value: float | None = 1.0, dtype=numpy.float32) -> NDArray:
+    def allocate(self, fill_value: float | None = 1.0, dtype: type[numpy.number] = numpy.float32) -> NDArray:
         """
         Allocate an ndarray for storing grid data.
 
@@ -194,5 +193,4 @@ class GridBase(Protocol):
         """
         if fill_value is None:
             return numpy.empty(self.cell_data_shape, dtype=dtype)
-        else:
-            return numpy.full(self.cell_data_shape, fill_value, dtype=dtype)
+        return numpy.full(self.cell_data_shape, fill_value, dtype=dtype)
diff --git a/gridlock/draw.py b/gridlock/draw.py
index e68fdc6..aa45200 100644
--- a/gridlock/draw.py
+++ b/gridlock/draw.py
@@ -1,7 +1,6 @@
 """
 Drawing-related methods for Grid class
 """
-from typing import Union
 from collections.abc import Sequence, Callable
 
 import numpy
@@ -20,7 +19,7 @@ from .position import GridPosMixin
 
 
 foreground_callable_t = Callable[[NDArray, NDArray, NDArray], NDArray]
-foreground_t = Union[float, foreground_callable_t]
+foreground_t = float | foreground_callable_t
 
 
 class GridDrawMixin(GridPosMixin):
@@ -166,7 +165,7 @@ class GridDrawMixin(GridPosMixin):
             # 2) Generate weights in z-direction
             w_z = numpy.zeros(((bdi_max - bdi_min + 1)[surface_normal], ))
 
-            def get_zi(offset, i=i, w_z=w_z):
+            def get_zi(offset: float, i=i, w_z=w_z) -> tuple[float, int]:          # noqa: ANN001
                 edges = self.shifted_exyz(i)[surface_normal]
                 point = center[surface_normal] + offset
                 grid_coord = numpy.digitize(point, edges) - 1
@@ -384,10 +383,10 @@ class GridDrawMixin(GridPosMixin):
             ind[direction] += 1                         # type: ignore #(known safe)
             foreground += mult[1] * grid[tuple(ind)]
 
-            def f_foreground(xs, ys, zs, i=i, foreground=foreground) -> NDArray[numpy.int_]:
+            def f_foreground(xs, ys, zs, i=i, foreground=foreground) -> NDArray[numpy.int64]:            # noqa: ANN001
                 # transform from natural position to index
                 xyzi = numpy.array([self.pos2ind(qrs, which_shifts=i)
-                                    for qrs in zip(xs.flat, ys.flat, zs.flat, strict=True)], dtype=int)
+                                    for qrs in zip(xs.flat, ys.flat, zs.flat, strict=True)], dtype=numpy.int64)
                 # reshape to original shape and keep only in-plane components
                 qi, ri = (numpy.reshape(xyzi[:, k], xs.shape) for k in surface)
                 return foreground[qi, ri]
diff --git a/gridlock/examples/ex0.py b/gridlock/examples/ex0.py
index 7dd4355..b96cdca 100644
--- a/gridlock/examples/ex0.py
+++ b/gridlock/examples/ex0.py
@@ -29,7 +29,7 @@ if __name__ == '__main__':
     #         numpy.linspace(-5.5, 5.5, 10)]
 
     half_x = [.25, .5, 0.75, 1, 1.25, 1.5, 2, 2.5, 3, 3.5]
-    xyz3 = [[-x for x in half_x[::-1]] + [0] + half_x,
+    xyz3 = [numpy.array([-x for x in half_x[::-1]] + [0] + half_x),
             numpy.linspace(-5.5, 5.5, 10),
             numpy.linspace(-5.5, 5.5, 10)]
     eg = Grid(xyz3)