diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index f7e09fd771eaf2..ce9e7f6d57dd3c 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -406,6 +406,7 @@ def test_setstate(self):
 
     def test_setstate_errors(self):
         f = self.partial(signature)
+
         self.assertRaises(TypeError, f.__setstate__, (capture, (), {}))
         self.assertRaises(TypeError, f.__setstate__, (capture, (), {}, {}, None))
         self.assertRaises(TypeError, f.__setstate__, [capture, (), {}, None])
@@ -413,6 +414,8 @@ def test_setstate_errors(self):
         self.assertRaises(TypeError, f.__setstate__, (capture, None, {}, None))
         self.assertRaises(TypeError, f.__setstate__, (capture, [], {}, None))
         self.assertRaises(TypeError, f.__setstate__, (capture, (), [], None))
+        self.assertRaises(TypeError, f.__setstate__, (capture, (), {}, ()))
+        self.assertRaises(TypeError, f.__setstate__, (capture, (), {}, 'test'))
 
     def test_setstate_subclasses(self):
         f = self.partial(signature)
diff --git a/Misc/NEWS.d/next/Library/2025-10-27-18-29-42.gh-issue-140590.LT9HHn.rst b/Misc/NEWS.d/next/Library/2025-10-27-18-29-42.gh-issue-140590.LT9HHn.rst
new file mode 100644
index 00000000000000..802183673cfacc
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2025-10-27-18-29-42.gh-issue-140590.LT9HHn.rst
@@ -0,0 +1,2 @@
+Fix arguments checking for the :meth:`!functools.partial.__setstate__` that
+may lead to internal state corruption and crash. Patch by Sergey Miryanov.
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index 3d45da493f4b3d..3420e7d8c37b74 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -699,7 +699,8 @@ partial_setstate(PyObject *self, PyObject *state)
     if (!PyArg_ParseTuple(state, "OOOO", &fn, &fnargs, &kw, &dict) ||
         !PyCallable_Check(fn) ||
         !PyTuple_Check(fnargs) ||
-        (kw != Py_None && !PyDict_Check(kw)))
+        (kw != Py_None && !PyDict_Check(kw)) ||
+        (dict != Py_None && !PyDict_Check(dict)))
     {
         PyErr_SetString(PyExc_TypeError, "invalid partial state");
         return NULL;