diff --git a/fatamorgana/basic.py b/fatamorgana/basic.py
index fee40dc..3c35d5e 100644
--- a/fatamorgana/basic.py
+++ b/fatamorgana/basic.py
@@ -2,7 +2,7 @@
 This module contains all datatypes and parsing/writing functions for
  all abstractions below the 'record' or 'block' level.
 """
-from typing import Any, IO, Union
+from typing import Any, IO, Union, TYPE_CHECKING
 from collections.abc import Sequence
 from fractions import Fraction
 from enum import Enum
@@ -250,6 +250,7 @@ def write_uint(stream: IO[bytes], n: int) -> int:
     Raises:
         SignedError: if `n` is negative.
     """
+    n = int(n)
     if n < 0:
         raise SignedError(f'uint must be positive: {n}')
 
@@ -295,6 +296,7 @@ def encode_sint(sint: int) -> int:
     Returns:
         Unsigned integer encoding for the input.
     """
+    sint = int(sint)
     return (abs(sint) << 1) | (sint < 0)
 
 
@@ -1595,7 +1597,7 @@ def read_point_list(
 
 def write_point_list(
         stream: IO[bytes],
-        points: list[Sequence[int]],
+        points: 'list[Sequence[int]] | NDArray',
         fast: bool = False,
         implicit_closed: bool = True
         ) -> int:
@@ -1618,6 +1620,8 @@ def write_point_list(
         Number of bytes written.
     """
     # If we're in a hurry, just write the points as arbitrary Deltas
+    if _USE_NUMPY:
+        points = numpy.asarray(points, dtype=int)
     if fast:
         size = write_uint(stream, 4)
         size += write_uint(stream, len(points))