diff --git a/src/_rtmidi.pyx b/src/_rtmidi.pyx
index 00c9e5c..7b32c9b 100644
--- a/src/_rtmidi.pyx
+++ b/src/_rtmidi.pyx
@@ -876,7 +876,7 @@ cdef class MidiIn(MidiBase):
         self.cancel_callback()
         MidiBase.close_port(self)
 
-    close_port.__doc__ == MidiBase.close_port.__doc__
+    close_port.__doc__ = MidiBase.close_port.__doc__
 
     def get_message(self):
         """Poll for MIDI input.
diff --git a/tests/test_basic.py b/tests/test_basic.py
index b971646..5a537c0 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -27,6 +27,9 @@ def test_get_api_name(self):
         self.assertEqual(rtmidi.get_api_name(rtmidi.API_WINDOWS_MM), 'winmm')
         self.assertEqual(rtmidi.get_api_name(rtmidi.API_WEB_MIDI), 'web')
 
+    def test_midiin_close_port_docstring(self):
+        self.assertEqual(rtmidi.MidiIn.close_port.__doc__, rtmidi._rtmidi.MidiBase.close_port.__doc__)
+
     def test_get_compiled_api(self):
         apilist = rtmidi.get_compiled_api()
         self.assertTrue(isinstance(apilist, list))