diff --git a/gridlock/draw.py b/gridlock/draw.py
index 2fb0b47..e10d4ff 100644
--- a/gridlock/draw.py
+++ b/gridlock/draw.py
@@ -53,7 +53,7 @@ class GridDrawMixin(GridPosMixin):
         if surface_normal not in range(3):
             raise GridError('Invalid surface_normal direction')
         center = numpy.squeeze(center)
-        poly_list = [numpy.array(poly, copy=False) for poly in polygons]
+        poly_list = [numpy.asarray(poly) for poly in polygons]
 
         # Check polygons, and remove redundant coordinates
         surface = numpy.delete(range(3), surface_normal)
@@ -293,7 +293,7 @@ class GridDrawMixin(GridPosMixin):
                  sizes of the cuboid
             foreground: Value to draw with ('brush color'). See `draw_polygons()` for details.
         """
-        dimensions = numpy.array(dimensions, copy=False)
+        dimensions = numpy.asarray(dimensions)
         p = numpy.array([[-dimensions[0], +dimensions[1]],
                          [+dimensions[0], +dimensions[1]],
                          [+dimensions[0], -dimensions[1]],
diff --git a/gridlock/grid.py b/gridlock/grid.py
index 91f3c6b..c8fe998 100644
--- a/gridlock/grid.py
+++ b/gridlock/grid.py
@@ -94,7 +94,7 @@ class Grid(GridDrawMixin, GridReadMixin, GridPosMixin):
         Raises:
             `GridError` on invalid input
         """
-        edge_arrs = [numpy.array(cc, copy=False) for cc in pixel_edge_coordinates]
+        edge_arrs = [numpy.asarray(cc) for cc in pixel_edge_coordinates]
         self.exyz = [numpy.unique(edges) for edges in edge_arrs]
         self.shifts = numpy.array(shifts, dtype=float)