diff --git a/cpplint/cpplint.py b/cpplint/cpplint.py
index 807da6b..4972f9d 100755
--- a/cpplint/cpplint.py
+++ b/cpplint/cpplint.py
@@ -655,13 +655,15 @@ class FileInfo:
         prefix = os.path.commonprefix([root_dir, project_dir])
         return fullname[len(prefix) + 1:]
 
-      # Not SVN? Try to find a git top level directory by searching up from the
-      # current path.
+      # Not SVN? Try to find a git or hg top level directory by searching up
+      # from the current path.
       root_dir = os.path.dirname(fullname)
       while (root_dir != os.path.dirname(root_dir) and
-             not os.path.exists(os.path.join(root_dir, ".git"))):
+             not os.path.exists(os.path.join(root_dir, ".git")) and
+             not os.path.exists(os.path.join(root_dir, ".hg"))):
         root_dir = os.path.dirname(root_dir)
-        if os.path.exists(os.path.join(root_dir, ".git")):
+        if (os.path.exists(os.path.join(root_dir, ".git")) or
+            os.path.exists(os.path.join(root_dir, ".hg"))):
           prefix = os.path.commonprefix([root_dir, project_dir])
           return fullname[len(prefix) + 1:]