diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 90ac4f6f6ee..5e993821ab2 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -372,6 +372,19 @@ class TestsWithSourceFile(unittest.TestCase):
         # remove the test file subdirectories
         shutil.rmtree(os.path.join(os.getcwd(), 'ziptest2dir'))
 
+    def zip_test_writestr_permissions(self, f, compression):
+        # Make sure that writestr creates files with mode 0600,
+        # when it is passed a name rather than a ZipInfo instance.
+
+        self.makeTestArchive(f, compression)
+        zipfp = zipfile.ZipFile(f, "r")
+        zinfo = zipfp.getinfo('strfile')
+        self.assertEqual(zinfo.external_attr, 0600 << 16)
+
+    def test_writestr_permissions(self):
+        for f in (TESTFN2, TemporaryFile(), StringIO()):
+            self.zip_test_writestr_permissions(f, zipfile.ZIP_STORED)
+
     def tearDown(self):
         os.remove(TESTFN)
         os.remove(TESTFN2)
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index ddeaa18c142..609dea3f273 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -1064,6 +1064,7 @@ class ZipFile:
             zinfo = ZipInfo(filename=zinfo_or_arcname,
                             date_time=time.localtime(time.time())[:6])
             zinfo.compress_type = self.compression
+            zinfo.external_attr = 0600 << 16
         else:
             zinfo = zinfo_or_arcname
 
diff --git a/Misc/NEWS b/Misc/NEWS
index 87ef02d3256..995c7c3b424 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -44,6 +44,10 @@ Library
 
 - Deprecate the sunaudio module for removal in Python 3.0.
 
+- Issue #3394: zipfile.writestr sets external attributes when passed a
+  file name rather than a ZipInfo instance, so files are extracted with
+  mode 0600 rather than 000 under Unix.
+
 
 What's New in Python 2.6 beta 2?
 ================================