diff --git a/ml_dtypes/_src/custom_float.h b/ml_dtypes/_src/custom_float.h
index 8bb7e9b6..9f292eba 100644
--- a/ml_dtypes/_src/custom_float.h
+++ b/ml_dtypes/_src/custom_float.h
@@ -401,7 +401,7 @@ PyArray_DescrProto GetCustomFloatDescrProto() {
       /*kind=*/TypeDescriptor<T>::kNpyDescrKind,
       /*type=*/TypeDescriptor<T>::kNpyDescrType,
       /*byteorder=*/TypeDescriptor<T>::kNpyDescrByteorder,
-      /*flags=*/NPY_USE_SETITEM,
+      /*flags=*/NPY_NEEDS_PYAPI | NPY_USE_SETITEM,
       /*type_num=*/0,
       /*elsize=*/sizeof(T),
       /*alignment=*/alignof(T),
diff --git a/ml_dtypes/_src/intn_numpy.h b/ml_dtypes/_src/intn_numpy.h
index 7d5dbe6f..e184e0b0 100644
--- a/ml_dtypes/_src/intn_numpy.h
+++ b/ml_dtypes/_src/intn_numpy.h
@@ -413,7 +413,7 @@ PyArray_DescrProto GetIntNDescrProto() {
       /*kind=*/TypeDescriptor<T>::kNpyDescrKind,
       /*type=*/TypeDescriptor<T>::kNpyDescrType,
       /*byteorder=*/TypeDescriptor<T>::kNpyDescrByteorder,
-      /*flags=*/NPY_USE_SETITEM,
+      /*flags=*/NPY_NEEDS_PYAPI | NPY_USE_SETITEM,
       /*type_num=*/0,
       /*elsize=*/sizeof(T),
       /*alignment=*/alignof(T),