diff --git a/patch_ng.py b/patch_ng.py
index 7e9444b..0ccbc82 100755
--- a/patch_ng.py
+++ b/patch_ng.py
@@ -56,6 +56,7 @@
 import posixpath
 import shutil
 import sys
+import stat
 
 
 PY3K = sys.version_info >= (3, 0)
@@ -178,6 +179,12 @@ def xstrip(filename):
       filename = re.sub(b'^[\\\\/]+', b'', filename)
   return filename
 
+
+def safe_unlink(filepath):
+  os.chmod(filepath, stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH)
+  os.unlink(filepath)
+
+
 #-----------------------------------------------
 # Main API functions
 
@@ -976,7 +983,7 @@ def apply(self, strip=0, root=None, fuzz=False):
         save(target, new_file)
       elif "dev/null" in target:
         source = self.strip_path(source, root, strip)
-        os.unlink(source)
+        safe_unlink(source)
       else:
         items.append(item)
     self.items = items
@@ -1106,12 +1113,12 @@ def apply(self, strip=0, root=None, fuzz=False):
           shutil.move(filenamen, backupname)
           if self.write_hunks(backupname if filenameo == filenamen else filenameo, filenamen, p.hunks):
             info("successfully patched %d/%d:\t %s" % (i+1, total, filenamen))
-            os.unlink(backupname)
+            safe_unlink(backupname)
             if new == b'/dev/null':
               # check that filename is of size 0 and delete it.
               if os.path.getsize(filenamen) > 0:
                 warning("expected patched file to be empty as it's marked as deletion:\t %s" % filenamen)
-              os.unlink(filenamen)
+              safe_unlink(filenamen)
           else:
             errors += 1
             warning("error patching file %s" % filenamen)
diff --git a/tests/11permission/11permission.patch b/tests/11permission/11permission.patch
new file mode 100644
index 0000000..8f959d2
--- /dev/null
+++ b/tests/11permission/11permission.patch
@@ -0,0 +1,10 @@
+--- some_file
++++ some_file
+@@ -2,6 +2,7 @@
+ line 2
+ line 3
+ line 4
++line 5
+ line 6
+ line 7
+ line 8
diff --git a/tests/11permission/[result]/some_file b/tests/11permission/[result]/some_file
new file mode 100644
index 0000000..fa2da6e
--- /dev/null
+++ b/tests/11permission/[result]/some_file
@@ -0,0 +1,10 @@
+line 1
+line 2
+line 3
+line 4
+line 5
+line 6
+line 7
+line 8
+line 9
+line 10
diff --git a/tests/11permission/some_file b/tests/11permission/some_file
new file mode 100644
index 0000000..c374ebd
--- /dev/null
+++ b/tests/11permission/some_file
@@ -0,0 +1,9 @@
+line 1
+line 2
+line 3
+line 4
+line 6
+line 7
+line 8
+line 9
+line 10
diff --git a/tests/run_tests.py b/tests/run_tests.py
index 3079381..6c16ef2 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -37,7 +37,8 @@
 import shutil
 import unittest
 import copy
-from os import listdir
+import stat
+from os import listdir, chmod
 from os.path import abspath, dirname, exists, join, isdir, isfile
 from tempfile import mkdtemp
 try:
@@ -171,9 +172,7 @@ def _run_test(self, testname):
         self._assert_dirs_equal(join(basepath, "[result]"),
                                 tmpdir,
                                 ignore=["%s.patch" % testname, ".svn", ".gitkeep", "[result]"])
-
-
-      shutil.rmtree(tmpdir)
+      remove_tree_force(tmpdir)
       return 0
 
 
@@ -362,7 +361,7 @@ def setUp(self):
 
     def tearDown(self):
         os.chdir(self.save_cwd)
-        shutil.rmtree(self.tmpdir)
+        remove_tree_force(self.tmpdir)
 
     def tmpcopy(self, filenames):
         """copy file(s) from test_dir to self.tmpdir"""
@@ -446,6 +445,17 @@ def test_fuzzy_patch_after(self):
         self.assertTrue(pto.apply(root=treeroot, fuzz=True))
         self.assertFalse(pto.apply(root=treeroot, fuzz=False))
 
+    def test_unlink_backup_windows(self):
+        """ Apply patch to a read-only file and don't change its filemode
+        """
+        treeroot = join(self.tmpdir, 'rootparent')
+        shutil.copytree(join(TESTS, '11permission'), treeroot)
+        pto = patch_ng.fromfile(join(TESTS, '11permission', '11permission.patch'))
+        some_file = join(treeroot, 'some_file')
+        chmod(some_file, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
+        self.assertTrue(pto.apply(root=treeroot))
+        self.assertTrue(os.stat(some_file).st_mode, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
+
 
 class TestHelpers(unittest.TestCase):
     # unittest setting
@@ -478,6 +488,12 @@ def test_pathstrip(self):
         self.assertEqual(patch_ng.pathstrip(b'path/name.diff', 1), b'name.diff')
         self.assertEqual(patch_ng.pathstrip(b'path/name.diff', 0), b'path/name.diff')
 
+def remove_tree_force(folder):
+    for root, _, files in os.walk(folder):
+        for it in files:
+            chmod(os.path.join(root, it), stat.S_IWUSR | stat.S_IWGRP | stat.S_IWOTH)
+    shutil.rmtree(folder, ignore_errors=True)
+
 # ----------------------------------------------------------------------------
 
 if __name__ == '__main__':