diff --git a/mypy/test/data.py b/mypy/test/data.py
index e886b11ffa8e..c4eefad6592c 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -10,7 +10,7 @@
 import sys
 
 import pytest
-from typing import List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
+from typing import Callable, List, Tuple, Set, Optional, Iterator, Any, Dict, NamedTuple, Union
 
 from mypy.test.config import test_data_prefix, test_temp_dir, PREFIX
 
@@ -35,6 +35,8 @@ def parse_test_case(case: 'DataDrivenTestCase') -> None:
     """
     test_items = parse_test_data(case.data, case.name)
     base_path = case.suite.base_path
+    # this file doesn't type-check on Windows without this line, see #11895
+    join: Callable[[str, str], str]
     if case.suite.native_sep:
         join = os.path.join
     else: