diff --git a/include/pybind11/detail/common.h b/include/pybind11/detail/common.h
index 83800e960b..9f8e13e24f 100644
--- a/include/pybind11/detail/common.h
+++ b/include/pybind11/detail/common.h
@@ -296,6 +296,10 @@ PYBIND11_WARNING_DISABLE_MSVC(4505)
 #    undef copysign
 #endif
 
+#if defined(PYBIND11_NUMPY_1_ONLY)
+#    define PYBIND11_INTERNAL_NUMPY_1_ONLY_DETECTED
+#endif
+
 #if defined(PYPY_VERSION) && !defined(PYBIND11_SIMPLE_GIL_MANAGEMENT)
 #    define PYBIND11_SIMPLE_GIL_MANAGEMENT
 #endif
diff --git a/include/pybind11/numpy.h b/include/pybind11/numpy.h
index c2dbd0607a..640c649ac7 100644
--- a/include/pybind11/numpy.h
+++ b/include/pybind11/numpy.h
@@ -29,6 +29,10 @@
 #include <utility>
 #include <vector>
 
+#if defined(PYBIND11_NUMPY_1_ONLY) && !defined(PYBIND11_INTERNAL_NUMPY_1_ONLY_DETECTED)
+#    error PYBIND11_NUMPY_1_ONLY must be defined before any pybind11 header is included.
+#endif
+
 /* This will be true on all flat address space platforms and allows us to reduce the
    whole npy_intp / ssize_t / Py_intptr_t business down to just ssize_t for all size
    and dimension types (e.g. shape, strides, indexing), instead of inflicting this