1 files changed, 6 insertions, 6 deletions

diff --git a/Lib/test/test__xxsubinterpreters.py b/Lib/test/test__xxsubinterpreters.py
index cf34fc3..7baea69 100644
--- a/Lib/test/test__xxsubinterpreters.py
+++ b/Lib/test/test__xxsubinterpreters.py
@@ -25,11 +25,11 @@ def _captured_script(script):
     indented = script.replace('\n', '\n                ')
     wrapped = dedent(f"""
         import contextlib
-        with open({w}, 'w') as spipe:
+        with open({w}, 'w', encoding="utf-8") as spipe:
             with contextlib.redirect_stdout(spipe):
                 {indented}
         """)
-    return wrapped, open(r)
+    return wrapped, open(r, encoding="utf-8")
 
 
 def _run_output(interp, request, shared=None):
@@ -45,7 +45,7 @@ def _running(interp):
     def run():
         interpreters.run_string(interp, dedent(f"""
             # wait for "signal"
-            with open({r}) as rpipe:
+            with open({r}, encoding="utf-8") as rpipe:
                 rpipe.read()
             """))
 
@@ -54,7 +54,7 @@ def _running(interp):
 
     yield
 
-    with open(w, 'w') as spipe:
+    with open(w, 'w', encoding="utf-8") as spipe:
         spipe.write('done')
     t.join()
 
@@ -806,7 +806,7 @@ class RunStringTests(TestBase):
     @unittest.skipUnless(hasattr(os, 'fork'), "test needs os.fork()")
     def test_fork(self):
         import tempfile
-        with tempfile.NamedTemporaryFile('w+') as file:
+        with tempfile.NamedTemporaryFile('w+', encoding="utf-8") as file:
             file.write('')
             file.flush()
 
@@ -816,7 +816,7 @@ class RunStringTests(TestBase):
                 try:
                     os.fork()
                 except RuntimeError:
-                    with open('{file.name}', 'w') as out:
+                    with open('{file.name}', 'w', encoding='utf-8') as out:
                         out.write('{expected}')
                 """)
             interpreters.run_string(self.id, script)