diff --git a/neo/rawio/blackrockrawio.py b/neo/rawio/blackrockrawio.py
index 83d1a2771..ee3920820 100644
--- a/neo/rawio/blackrockrawio.py
+++ b/neo/rawio/blackrockrawio.py
@@ -1683,7 +1683,8 @@ def _read_nev_data(self, spec, filename):
             The NEV filename to read from
         """
         packet_size_bytes = self._nev_basic_header["bytes_in_data_packets"]
-        header_size = self._nev_basic_header["bytes_in_headers"]
+        # int(): a uint32 scalar overflows against file sizes > 4 GiB under NumPy 2 (NEP 50)
+        header_size = int(self._nev_basic_header["bytes_in_headers"])
 
         if self._nev_basic_header["ver_major"] >= 3:
             ts_format = "uint64"
@@ -1995,7 +1996,7 @@ def _get_nev_rec_times(self):
         filename = ".".join([self._filenames["nev"], "nev"])
 
         dt = [("timestamp", "uint32")]
-        offset = self._get_file_size(filename) - self._nev_params("bytes_in_data_packets")
+        offset = self._get_file_size(filename) - int(self._nev_params("bytes_in_data_packets"))
         last_data_packet = np.memmap(filename, offset=offset, dtype=dt, mode="r")[0]
 
         n_starts = [0 * self._nev_params("event_unit")]
diff --git a/neo/test/rawiotest/test_blackrockrawio.py b/neo/test/rawiotest/test_blackrockrawio.py
index 03c3481ae..20e69e3c9 100644
--- a/neo/test/rawiotest/test_blackrockrawio.py
+++ b/neo/test/rawiotest/test_blackrockrawio.py
@@ -3,6 +3,7 @@
 """
 
 import unittest
+from unittest import mock
 
 from neo.rawio.blackrockrawio import BlackrockRawIO
 from neo.test.rawiotest.common_rawio_test import BaseTestRawIO
@@ -374,6 +375,37 @@ def test_gap_tolerance_ms_parameter(self):
         segments_strict = reader_strict.segment_count(0)
         self.assertEqual(segments_strict, 3)  #
 
+    def test_nev_over_4_gib_does_not_overflow(self):
+        """File sizes > 4 GiB must not overflow against the uint32 NEV header fields (NumPy 2, NEP 50)."""
+        file_size = 5 * 2**30
+        basic_header = np.zeros(
+            1, dtype=[("ver_major", "uint8"), ("bytes_in_headers", "uint32"), ("bytes_in_data_packets", "uint32")]
+        )[0]
+        basic_header["ver_major"] = 2
+        basic_header["bytes_in_headers"] = 1000
+        basic_header["bytes_in_data_packets"] = 104
+
+        reader = BlackrockRawIO.__new__(BlackrockRawIO)  # skip parsing real files
+        reader._nev_basic_header = basic_header
+        reader._nev_params = lambda name: basic_header[name]
+        reader._filenames = {"nev": "fake"}
+
+        class Stop(Exception):
+            pass
+
+        with (
+            mock.patch.object(reader, "_get_file_size", return_value=file_size),
+            mock.patch("neo.rawio.blackrockrawio.np.memmap", side_effect=Stop) as memmap,
+        ):
+            with self.assertRaises(Stop):
+                reader._read_nev_data("2.2", "fake.nev")
+            self.assertEqual(memmap.call_args.kwargs["offset"], 1000)
+            self.assertEqual(memmap.call_args.kwargs["shape"], ((file_size - 1000) // 104,))
+
+            with self.assertRaises(Stop):
+                reader._get_nev_rec_times()
+            self.assertEqual(memmap.call_args.kwargs["offset"], file_size - 104)
+
 
 if __name__ == "__main__":
     unittest.main()