diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 24e8e772491..f8253531730 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -532,6 +532,9 @@ class UnicodeTest(
 
         self.assertEqual(unicode('+3ADYAA-', 'utf-7', 'replace'), u'\ufffd')
 
+        # Issue #2242: crash on some Windows/MSVC versions
+        self.assertRaises(UnicodeDecodeError, '+\xc1'.decode, 'utf-7')
+
     def test_codecs_utf8(self):
         self.assertEqual(u''.encode('utf-8'), '')
         self.assertEqual(u'\u20ac'.encode('utf-8'), '\xe2\x82\xac')
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index a62e92908dc..16d97c34570 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -1523,7 +1523,7 @@ PyObject *PyUnicode_DecodeUTF7Stateful(const char *s,
     while (s < e) {
         Py_UNICODE ch;
         restart:
-        ch = *s;
+        ch = (unsigned char) *s;
 
         if (inShift) {
             if ((ch == '-') || !B64CHAR(ch)) {