diff --git a/musicpy/structures.py b/musicpy/structures.py
index 892a44f..8f1364d 100644
--- a/musicpy/structures.py
+++ b/musicpy/structures.py
@@ -1682,7 +1682,7 @@ def pitch_inversion(self):
                                           temp.get_duration(), temp.interval,
                                           False)
         result.set_volume(volumes)
-        result += pitch_bend_changes
+        result.pitch_bends += pitch_bend_changes
         return result
 
     def normalize_tempo(self,
diff --git a/setup.py b/setup.py
index 85b80bf..2113216 100644
--- a/setup.py
+++ b/setup.py
@@ -4,7 +4,7 @@
     name='musicpy',
     packages=find_packages(),
     package_data={'musicpy': ['./*']},
-    version='6.86',
+    version='6.87',
     license='LGPLv2.1',
     description=
     'Musicpy is a music programming language in Python designed to write music in very handy syntax through music theory and algorithms.',
@@ -12,7 +12,7 @@
     author_email='1036889495@qq.com',
     url='https://github.com/Rainbow-Dreamer/musicpy.git',
     download_url=
-    'https://github.com/Rainbow-Dreamer/musicpy/archive/6.86.tar.gz',
+    'https://github.com/Rainbow-Dreamer/musicpy/archive/6.87.tar.gz',
     keywords=[
         'music language', 'use codes to write music', 'music language for AI'
     ],