diff --git a/openstack_requirements/cmds/edit_constraint.py b/openstack_requirements/cmds/edit_constraint.py
index e1bb602449..bf02cc512e 100644
--- a/openstack_requirements/cmds/edit_constraint.py
+++ b/openstack_requirements/cmds/edit_constraint.py
@@ -71,5 +71,7 @@ def main(argv=None, stdout=None):
     out = requirement.to_content(out_reqs, prefix=False)
     with open(args[0] + '.tmp', 'wt') as f:
         f.write(out)
+    if os.path.exists(args[0]):
+        os.remove(args[0])
     os.rename(args[0] + '.tmp', args[0])
     return 0
diff --git a/openstack_requirements/project.py b/openstack_requirements/project.py
index e7e605e7f8..8c9e61d4d7 100644
--- a/openstack_requirements/project.py
+++ b/openstack_requirements/project.py
@@ -105,7 +105,7 @@ def _safe_read(project, filename, output=None):
     if output is None:
         output = project
     try:
-        path = project['root'] + '/' + filename
+        path = os.path.join(project['root'], filename)
         with io.open(path, 'rt', encoding="utf-8") as f:
             output[filename] = f.read()
     except IOError as e:
@@ -166,10 +166,12 @@ def write(project, actions, stdout, verbose, noop=False):
         elif type(action) is File:
             if noop:
                 continue
-            fullname = project['root'] + '/' + action.filename
+            fullname = os.path.join(project['root'], action.filename)
             tmpname = fullname + '.tmp'
             with open(tmpname, 'wt') as f:
                 f.write(action.content)
+            if os.path.exists(fullname):
+                os.remove(fullname)
             os.rename(tmpname, fullname)
         elif type(action) is StdOut:
             stdout.write(action.message)
diff --git a/setup.cfg b/setup.cfg
index d24b1e64b3..49f6a121f0 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -12,6 +12,7 @@ classifier =
     Intended Audience :: System Administrators
     License :: OSI Approved :: Apache Software License
     Operating System :: POSIX :: Linux
+    Operating System :: Microsoft :: Windows
     Programming Language :: Python
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7