diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index 62edd6c..907f943 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -564,6 +564,14 @@
     def test_execvpe_with_bad_arglist(self):
         self.assertRaises(ValueError, os.execvpe, 'notepad', [], None)
 
+class ArgTests(unittest.TestCase):
+    def test_bytearray(self):
+        # Issue #7561: posix module didn't release bytearray exports properly.
+        b = bytearray(os.sep.encode('ascii'))
+        self.assertRaises(OSError, os.mkdir, b)
+        # Check object is still resizable.
+        b[:] = b''
+
 class Win32ErrorTests(unittest.TestCase):
     def test_rename(self):
         self.assertRaises(WindowsError, os.rename, support.TESTFN, support.TESTFN+".bak")
@@ -750,6 +758,7 @@
 
 def test_main():
     support.run_unittest(
+        ArgTests,
         FileTests,
         StatAttributeTests,
         EnvironTests,
diff --git a/Misc/NEWS b/Misc/NEWS
index e77e8a7..c3a9f5c 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -67,6 +67,9 @@
 Library
 -------
 
+- Issue #7561: Fix crashes when using bytearray objects with the posix
+  module.
+
 - Issue #1670765: Prevent email.generator.Generator from re-wrapping
   headers in multipart/signed MIME parts, which fixes one of the sources of
   invalid modifications to such parts by Generator.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index 688da2c..814c9ba 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -580,7 +580,7 @@
 release_bytes(PyObject* o)
 {
 	if (PyByteArray_Check(o))
-		o->ob_type->tp_as_buffer->bf_releasebuffer(NULL, 0);
+		o->ob_type->tp_as_buffer->bf_releasebuffer(o, 0);
 	Py_DECREF(o);
 }