diff --git a/src/tree.c b/src/tree.c
index 13309be..4ffa5c9 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -332,21 +332,29 @@ Tree_diff_to_tree(Tree *self, PyObject *args, PyObject *kwds)
 {
     git_diff_options opts = GIT_DIFF_OPTIONS_INIT;
     git_diff_list *diff;
-    git_tree* tree;
+    git_tree *from, *to, *tmp;
     git_repository* repo;
-    int err;
-    char *keywords[] = {"obj", "flags", NULL};
+    int err, swap = 0;
+    char *keywords[] = {"obj", "flags", "swap", NULL};
 
     Diff *py_diff;
     Tree *py_tree = NULL;
 
-    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O!i", keywords,
-                                     &TreeType, &py_tree, &opts.flags))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O!ii", keywords,
+                                     &TreeType, &py_tree, &opts.flags,
+                                     &swap))
         return NULL;
 
     repo = self->repo->repo;
-    tree = (py_tree == NULL) ? NULL : py_tree->tree;
-    err = git_diff_tree_to_tree(&diff, repo, self->tree, tree, &opts);
+    to = (py_tree == NULL) ? NULL : py_tree->tree;
+    from = self->tree;
+    if (swap > 0) {
+      tmp = from;
+      from = to;
+      to = tmp;
+    }
+
+    err = git_diff_tree_to_tree(&diff, repo, from, to, &opts);
 
     if (err < 0)
         return Error_set(err);
diff --git a/test/test_diff.py b/test/test_diff.py
index d68d7ed..b336624 100644
--- a/test/test_diff.py
+++ b/test/test_diff.py
@@ -33,6 +33,7 @@ import unittest
 import pygit2
 from pygit2 import GIT_DIFF_INCLUDE_UNMODIFIED
 from . import utils
+from itertools import chain
 
 
 COMMIT_SHA1_1 = '5fe808e8953c12735680c257f56600cb0de44b10'
@@ -145,8 +146,20 @@ class DiffTest(utils.BareRepoTestCase):
     def test_diff_empty_tree(self):
         commit_a = self.repo[COMMIT_SHA1_1]
         diff = commit_a.tree.diff_to_tree()
+
+        def get_context_for_lines(diff):
+          hunks = chain(*map(lambda x: x.hunks, [p for p in diff]))
+          lines = chain(*map(lambda x: x.lines, hunks))
+          return map(lambda x: x[0], lines)
+
         entries = [p.new_file_path for p in diff]
         self.assertAll(lambda x: commit_a.tree[x], entries)
+        self.assertAll(lambda x: '-' == x, get_context_for_lines(diff))
+
+        diff_swaped = commit_a.tree.diff_to_tree(swap=True)
+        entries = [p.new_file_path for p in diff_swaped]
+        self.assertAll(lambda x: commit_a.tree[x], entries)
+        self.assertAll(lambda x: '+' == x, get_context_for_lines(diff_swaped))
 
     def test_diff_tree_opts(self):
         commit_c = self.repo[COMMIT_SHA1_3]