diff --git a/pyproject.toml b/pyproject.toml
index 2fa8382..1d6bdd1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -6,8 +6,9 @@ requires = [
     "Cython>=3.0, <3.1",
 
     # TODO: simplify numpy requirement after numpy 1.26.0 final is released
-    "oldest-supported-numpy ; python_version < '3.12.0rc1'",
-    "numpy>=1.26.0b1 ; python_version >= '3.12.0rc1'",
+    "oldest-supported-numpy ; python_version < '3.9'",
+    "numpy>=1.25, <2.0 ; python_version >= '3.9' and python_version < '3.12.0rc1'",
+    "numpy>=1.26.0b1, <2.0; python_version >= '3.12.0rc1'",
 ]
 
 [project]
@@ -24,6 +25,8 @@ dependencies = [
   # match the absolute oldest version of numpy with *any*
   # level of support for our minimal Python requirement
   # https://github.com/scipy/oldest-supported-numpy/issues/76#issuecomment-1628865694
+
+  # after Python 3.8 is dropped, keep in sync with NPY_TARGET_VERSION (setup.py)
   "numpy>=1.17.3,<2.0",
 ]
 classifiers = [
diff --git a/setup.py b/setup.py
index 74a5c4f..b2fca1b 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,5 @@
 import os
+import sys
 
 import numpy as np
 from Cython.Build import cythonize
@@ -16,7 +17,14 @@
 else:
     std_libs = ["m"]
 
-define_macros = [("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION")]
+define_macros = [
+    ("NPY_NO_DEPRECATED_API", "NPY_1_7_API_VERSION"),
+]
+if sys.version_info >= (3, 9):
+    # keep in sync with runtime requirements (pyproject.toml)
+    define_macros.append(("NPY_TARGET_VERSION", "NPY_1_18_API_VERSION"))
+else:
+    pass
 
 extensions = [
     Extension(