diff --git a/Lib/lib2to3/fixes/fix_types.py b/Lib/lib2to3/fixes/fix_types.py
--- a/Lib/lib2to3/fixes/fix_types.py
+++ b/Lib/lib2to3/fixes/fix_types.py
@@ -42,7 +42,7 @@
         'NotImplementedType' : 'type(NotImplemented)',
         'SliceType' : 'slice',
         'StringType': 'bytes', # XXX ?
-        'StringTypes' : 'str', # XXX ?
+        'StringTypes' : '(str,)', # XXX ?
         'TupleType': 'tuple',
         'TypeType' : 'type',
         'UnicodeType': 'str',
diff --git a/Lib/lib2to3/tests/test_fixers.py b/Lib/lib2to3/tests/test_fixers.py
--- a/Lib/lib2to3/tests/test_fixers.py
+++ b/Lib/lib2to3/tests/test_fixers.py
@@ -3214,6 +3214,10 @@
         a = """type(None)"""
         self.check(b, a)
 
+        b = "types.StringTypes"
+        a = "(str,)"
+        self.check(b, a)
+
 class Test_idioms(FixerTestCase):
     fixer = "idioms"