diff --git a/erfa/ufunc.c.templ b/erfa/ufunc.c.templ
index 98bdbb5..ae7c45d 100644
--- a/erfa/ufunc.c.templ
+++ b/erfa/ufunc.c.templ
@@ -17,6 +17,11 @@
 #include "erfa.h"
 #include "erfaextra.h"
 
+// Backported NumPy 2 API (can be removed if numpy 2 is required)
+#if NPY_ABI_VERSION < 0x02000000
+#define PyDataType_ELSIZE(descr) ((descr)->elsize)
+#endif
+
 // On gcc<10 we can run into the following:
 //
 //   error: dereferencing pointer to incomplete type 'PyTypeObject'
diff --git a/pyproject.toml b/pyproject.toml
index 287447c..0b46469 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,6 +3,6 @@ requires = [
     "setuptools",
     "setuptools_scm>=6.2",
     "jinja2>=2.10.3",
-    "numpy"
+    "numpy>=1.25",
 ]
 build-backend = 'setuptools.build_meta'