# HG changeset patch
# Parent 9f75f82d623e25e1f58665a781cf6d304b6e40b8

diff --git a/Tools/scripts/patchcheck.py b/Tools/scripts/patchcheck.py
--- a/Tools/scripts/patchcheck.py
+++ b/Tools/scripts/patchcheck.py
@@ -28,20 +28,34 @@ def status(message, modal=False, info=No
 @status("Getting the list of files that have been added/changed",
             info=lambda x: "%s files" % len(x))
 def changed_files():
-    """Run ``svn status`` and return a set of files that have been
-    changed/added."""
-    cmd = 'svn status --quiet --non-interactive --ignore-externals'
-    svn_st = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE)
-    svn_st.wait()
-    output = [x.decode().rstrip() for x in svn_st.stdout.readlines()]
-    files = set()
+    """Get the list of files that have been changed/added."""
+    if os.path.isdir('.hg'):
+        vcs = 'Mercurial'
+    elif os.path.isdir('.svn'):
+        vcs = 'Subversion'
+    else:
+        sys.exit("can't get the list of modified files without "
+                 "a svn or hg checkout")
+
+    if vcs == 'Mercurial':
+        cmd = 'hg status --added --modified --no-status'
+    else:
+        cmd = 'svn status --quiet --non-interactive --ignore-externals'
+    status = subprocess.Popen(cmd.split(' '), stdout=subprocess.PIPE)
+    status.wait()
+    output = (x.decode().rstrip() for x in status.stdout)
+
+    if vcs == 'Mercurial':
+        return list(output)
+
+    files = list()
     for line in output:
-        if not line[0] in ('A', 'M'):
+        if not line.startswith(('A', 'M')):
             continue
         line_parts = line.split()
         path = line_parts[-1]
         if os.path.isfile(path):
-            files.add(path)
+            files.append(path)
     return files
 
 @status("Fixing whitespace", info=lambda x: "%s files" % x)