diff --git a/pyproject.toml b/pyproject.toml
index dd523fb..c74d140 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,14 +1,6 @@
 [build-system]
-requires = [
-  'cython',
-  'oldest-supported-numpy',
-  'setuptools',
-  'wheel',
-]
+requires = ['cython', 'numpy', 'setuptools', 'wheel']
 build-backend = 'setuptools.build_meta'
 
 [tool.cranko]
-annotated_files = [
-  "docs/conf.py",
-  "toasty/cli.py",
-]
+annotated_files = ["docs/conf.py", "toasty/cli.py"]
diff --git a/setup.py b/setup.py
index aed36bc..516ba05 100644
--- a/setup.py
+++ b/setup.py
@@ -94,7 +94,11 @@ setup_args = dict(
         "build_ext": build_ext,
     },
     ext_modules=[
-        Extension("toasty._libtoasty", ["toasty/_libtoasty.pyx"]),
+        Extension(
+            "toasty._libtoasty",
+            ["toasty/_libtoasty.pyx"],
+            define_macros=[("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION")],
+        ),
     ],
     include_dirs=[
         np.get_include(),
diff --git a/toasty/_libtoasty.pyx b/toasty/_libtoasty.pyx
index 70e4dad..762a0aa 100644
--- a/toasty/_libtoasty.pyx
+++ b/toasty/_libtoasty.pyx
@@ -1,9 +1,11 @@
 from libc.math cimport sin, cos, atan2, hypot
-import numpy as np
 
 cimport cython
 
 cimport numpy as np
+import numpy as np
+
+np.import_array()
 
 DTYPE = np.float64
 ctypedef np.float64_t DTYPE_t
diff --git a/toasty/samplers.py b/toasty/samplers.py
index b68e633..e5c7492 100644
--- a/toasty/samplers.py
+++ b/toasty/samplers.py
@@ -152,7 +152,8 @@ def healpix_fits_file_sampler(
         # needed.
         data = data[data.dtype.names[0]]
         if data.dtype.byteorder not in "=|":
-            data = data.byteswap().newbyteorder()
+            data = data.byteswap()
+            data = data.view(data.dtype.newbyteorder())
 
         nest = hdr.get("ORDERING") == "NESTED"
         coord = hdr.get("COORDSYS", "C")