diff --git a/pyproject.toml b/pyproject.toml
index 3e441ab74f..5378a2201e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,9 +2,8 @@
 requires = [
 	"setuptools >= 65",
 	"Cython",
-	'oldest-supported-numpy',
+	'numpy>=2.0.0rc1',
 	'setuptools_scm[toml] >= 8',
-	"extension-helpers",
 ]
 build-backend = "setuptools.build_meta"
 
@@ -33,3 +32,17 @@ filterwarnings = [
     "error::gammapy.utils.deprecation.GammapyDeprecationWarning",
     "error::matplotlib.MatplotlibDeprecationWarning",
 ]
+
+
+[tool.setuptools_scm]
+version_file = "gammapy/version.py"
+version_file_template = """\
+# Note that we need to fall back to the hard-coded version if either
+# setuptools_scm can't be imported or setuptools_scm can't determine the
+# version, so we catch the generic 'Exception'.
+try:
+    from setuptools_scm import get_version
+    version = get_version(root='..', relative_to=__file__)
+except Exception:
+    version = '{version}'
+"""
diff --git a/setup.py b/setup.py
index 935cc1e5cf..af6ab33e7e 100755
--- a/setup.py
+++ b/setup.py
@@ -3,11 +3,7 @@
 
 # NOTE: The configuration for the package, including the name, version, and
 # other information are set in the setup.cfg file.
-
-import os
 import sys
-from extension_helpers import get_extensions
-from setuptools import setup
 
 # First provide helpful messages if contributors try and run legacy commands
 # for tests or docs.
@@ -62,21 +58,31 @@
     print(DOCS_HELP)
     sys.exit(1)
 
-VERSION_TEMPLATE = """
-# Note that we need to fall back to the hard-coded version if either
-# setuptools_scm can't be imported or setuptools_scm can't determine the
-# version, so we catch the generic 'Exception'.
-try:
-    from setuptools_scm import get_version
-    version = get_version(root='..', relative_to=__file__)
-except Exception:
-    version = '{version}'
-""".lstrip()
+
+# imports here so that people get the nice error messages above without needing
+# build dependencies
+import numpy as np  # noqa: E402
+from Cython.Build import cythonize  # noqa: E402
+from setuptools import Extension, setup  # noqa: E402
+
+kwargs = dict(
+    include_dirs=[np.get_include()],
+    define_macros=[
+        # fixes a warning when compiling
+        ("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION"),
+        # defines the oldest numpy we want to be compatible with
+        ("NPY_TARGET_VERSION", "NPY_1_21_API_VERSION"),
+    ],
+)
+
+extensions = [
+    Extension(
+        "gammapy.stats.fit_statistics_cython",
+        sources=["gammapy/stats/fit_statistics_cython.pyx"],
+        **kwargs,
+    ),
+]
 
 setup(
-    use_scm_version={
-        "write_to": os.path.join("gammapy", "version.py"),
-        "write_to_template": VERSION_TEMPLATE,
-    },
-    ext_modules=get_extensions(),
+    ext_modules=cythonize(extensions),
 )