python · serhiy-storchaka · Aug 9, 2026 · May 20, 2018 · Aug 9, 2026 · serhiy-storchaka
diff --git a/Lib/test/test_mmap.py b/Lib/test/test_mmap.py
@@ -59,6 +59,7 @@ def test_basic(self):
             f.flush()
             m = mmap.mmap(f.fileno(), 2 * PAGESIZE)
             self.addCleanup(m.close)
+            self.assertEqual(f.tell(), 2 * PAGESIZE)
         finally:
             f.close()
 

diff --git a/Misc/NEWS.d/next/Windows/2026-08-09-17-30-00.gh-issue-68048.Mq8Vd4.rst b/Misc/NEWS.d/next/Windows/2026-08-09-17-30-00.gh-issue-68048.Mq8Vd4.rst
@@ -0,0 +1,2 @@
+Creating a :class:`mmap.mmap` object on Windows no longer resets the position
+of the underlying file to zero, as on other platforms.
diff --git a/Modules/mmapmodule.c b/Modules/mmapmodule.c
@@ -2084,9 +2084,6 @@ new_mmap_object(PyTypeObject *type, PyObject *args, PyObject *kwdict)
         fh = _Py_get_osfhandle(fileno);
         if (fh == INVALID_HANDLE_VALUE)
             return NULL;
-
-        /* Win9x appears to need us seeked to zero */
-        lseek(fileno, 0, SEEK_SET);
     }
 
     m_obj = (mmap_object *)type->tp_alloc(type, 0);
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Creating a :class:`mmap.mmap` object on Windows no longer resets the position
		of the underlying file to zero, as on other platforms.