diff --git a/src/ttmask/cuboid.py b/src/ttmask/cuboid.py
index e1f8a2e..ca6f56c 100644
--- a/src/ttmask/cuboid.py
+++ b/src/ttmask/cuboid.py
@@ -13,6 +13,7 @@ def cuboid(
     boxsize: int = typer.Option(...),
     cuboid_sidelengths: Annotated[Tuple[float, float, float], typer.Option()] = (None, None, None),
     soft_edge_size: float = typer.Option(...),
+    mrc_voxel_size: float = typer.Option(...),
 ):
     c = boxsize // 2
     center = np.array([c, c, c])
@@ -47,4 +48,4 @@ def cuboid(
 
     mask[boundary_pixels] = (0.5 * np.cos(normalised_distance_from_edge) + 0.5)
 
-    mrcfile.write("cuboid.mrc", mask, voxel_size=4, overwrite=True)
+    mrcfile.write("cuboid.mrc", mask, voxel_size= mrc_voxel_size, overwrite=True)
diff --git a/src/ttmask/cylinder.py b/src/ttmask/cylinder.py
index 2a64311..d7c9fbd 100644
--- a/src/ttmask/cylinder.py
+++ b/src/ttmask/cylinder.py
@@ -13,6 +13,7 @@ def cylinder(
     cylinder_outer_diameter: float = typer.Option(...),
     cylinder_inner_diameter: float = typer.Option(0),
     soft_edge_size: int = typer.Option(...),
+    mrc_voxel_size: float = typer.Option(...),
 ):
     cylinder_outer_radius = cylinder_outer_diameter / 2
     cylinder_inner_radius = cylinder_inner_diameter / 2
@@ -43,4 +44,5 @@ def cylinder(
 
     mask[boundary_pixels] = (0.5 * np.cos(normalised_distance_from_edge) + 0.5)
 
-    mrcfile.write("cylinder.mrc", mask, voxel_size=4, overwrite=True)
+    mrcfile.write("cylinder.mrc", mask, voxel_size= mrc_voxel_size, overwrite=True)
+
diff --git a/src/ttmask/sphere.py b/src/ttmask/sphere.py
index 8fdf5b3..8e7eda9 100644
--- a/src/ttmask/sphere.py
+++ b/src/ttmask/sphere.py
@@ -11,6 +11,7 @@ def sphere(
     boxsize: int = typer.Option(...),
     sphere_diameter: float = typer.Option(...),
     soft_edge_size: int = typer.Option(...),
+    mrc_voxel_size: float = typer.Option(...),
 ):
     sphere_radius = sphere_diameter / 2
     c = boxsize // 2
@@ -38,4 +39,4 @@ def sphere(
 
     mask[boundary_pixels] = (0.5 * np.cos(normalised_distance_from_edge) + 0.5)
 
-    mrcfile.write("sphere.mrc", mask, voxel_size=4, overwrite=True)
+    mrcfile.write("sphere.mrc", mask, voxel_size= mrc_voxel_size, overwrite=True)