diff --git a/src/gpgi/_data_types.py b/src/gpgi/_data_types.py
index 62af0ef..4b4fc9b 100644
--- a/src/gpgi/_data_types.py
+++ b/src/gpgi/_data_types.py
@@ -491,10 +491,10 @@ def _validate(self) -> None:
                 f"- from particles: {self.particles.dtype}\n"
             )
 
-    def _get_padded_cell_edges(self) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
+    def _get_padded_cell_edges(self) -> tuple[RealArray, RealArray, RealArray]:
         edges = iter(self.grid.cell_edges.values())
 
-        def pad(a: np.ndarray) -> np.ndarray:
+        def pad(a: RealArray) -> RealArray:
             dx = a[1] - a[0]
             return np.concatenate([[a[0] - dx], a, [a[-1] + dx]])
 
@@ -510,7 +510,7 @@ def pad(a: np.ndarray) -> np.ndarray:
 
         return cell_edges_x1, cell_edges_x2, cell_edges_x3
 
-    def _get_3D_particle_coordinates(self) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
+    def _get_3D_particle_coordinates(self) -> tuple[RealArray, RealArray, RealArray]:
         particle_coords = iter(self.particles.coordinates.values())
         particles_x1 = next(particle_coords)
         DTYPE = particles_x1.dtype
@@ -588,9 +588,7 @@ def _validate_sort_axes(self, axes: tuple[int, ...]) -> None:
         if any(axis > self.grid.ndim - 1 for axis in axes):
             raise ValueError(f"Expected all axes to be <{self.grid.ndim}, got {axes!r}")
 
-    def _get_sort_key(
-        self, axes: tuple[int, ...]
-    ) -> np.ndarray[Any, np.dtype[np.uint16]]:
+    def _get_sort_key(self, axes: tuple[int, ...]) -> NDArray[np.uint16]:
         self._validate_sort_axes(axes)
 
         hci = self.host_cell_index
diff --git a/src/gpgi/_typing.py b/src/gpgi/_typing.py
index 5cfdc94..2d0145a 100644
--- a/src/gpgi/_typing.py
+++ b/src/gpgi/_typing.py
@@ -1,61 +1,61 @@
-from typing import NotRequired, TypedDict, TypeVar
+from typing import Generic, NotRequired, TypedDict, TypeVar
 
 import numpy as np
-import numpy.typing as npt
+from numpy.typing import NDArray
 
-Real = TypeVar("Real", np.float32, np.float64)
-RealArray = npt.NDArray[Real]
-HCIArray = npt.NDArray[np.uint16]
+RealT = TypeVar("RealT", np.float32, np.float64)
+RealArray = NDArray[RealT]
+HCIArray = NDArray[np.uint16]
 
 
 Name = str
-FieldMap = dict[str, np.ndarray]
+FieldMap = dict[str, NDArray[RealT]]
 
 
-class CartesianCoordinates(TypedDict):
-    x: np.ndarray
-    y: NotRequired[np.ndarray]
-    z: NotRequired[np.ndarray]
+class CartesianCoordinates(TypedDict, Generic[RealT]):
+    x: NDArray[RealT]
+    y: NotRequired[NDArray[RealT]]
+    z: NotRequired[NDArray[RealT]]
 
 
-class CylindricalCoordinates(TypedDict):
-    radius: np.ndarray
-    azimuth: NotRequired[np.ndarray]
-    z: NotRequired[np.ndarray]
+class CylindricalCoordinates(TypedDict, Generic[RealT]):
+    radius: NDArray[RealT]
+    azimuth: NotRequired[NDArray[RealT]]
+    z: NotRequired[NDArray[RealT]]
 
 
-class PolarCoordinates(TypedDict):
-    radius: np.ndarray
-    z: NotRequired[np.ndarray]
-    azimuth: NotRequired[np.ndarray]
+class PolarCoordinates(TypedDict, Generic[RealT]):
+    radius: NDArray[RealT]
+    z: NotRequired[NDArray[RealT]]
+    azimuth: NotRequired[NDArray[RealT]]
 
 
-class SphericalCoordinates(TypedDict):
-    colatitude: np.ndarray
-    radius: NotRequired[np.ndarray]
-    azimuth: NotRequired[np.ndarray]
+class SphericalCoordinates(TypedDict, Generic[RealT]):
+    colatitude: NDArray[RealT]
+    radius: NotRequired[NDArray[RealT]]
+    azimuth: NotRequired[NDArray[RealT]]
 
 
-class EquatorialCoordinates(TypedDict):
-    radius: np.ndarray
-    latitude: NotRequired[np.ndarray]
-    azimuth: NotRequired[np.ndarray]
+class EquatorialCoordinates(TypedDict, Generic[RealT]):
+    radius: NDArray[RealT]
+    latitude: NotRequired[NDArray[RealT]]
+    azimuth: NotRequired[NDArray[RealT]]
 
 
 CoordMap = (
-    CartesianCoordinates
-    | CylindricalCoordinates
-    | PolarCoordinates
-    | SphericalCoordinates
-    | EquatorialCoordinates
+    CartesianCoordinates[RealT]
+    | CylindricalCoordinates[RealT]
+    | PolarCoordinates[RealT]
+    | SphericalCoordinates[RealT]
+    | EquatorialCoordinates[RealT]
 )
 
 
-class GridDict(TypedDict):
-    cell_edges: CoordMap
-    fields: NotRequired[FieldMap]
+class GridDict(TypedDict, Generic[RealT]):
+    cell_edges: CoordMap[RealT]
+    fields: NotRequired[FieldMap[RealT]]
 
 
-class ParticleSetDict(TypedDict):
-    coordinates: CoordMap
-    fields: NotRequired[FieldMap]
+class ParticleSetDict(TypedDict, Generic[RealT]):
+    coordinates: CoordMap[RealT]
+    fields: NotRequired[FieldMap[RealT]]