diff --git a/partitura/io/exportmusicxml.py b/partitura/io/exportmusicxml.py
index 9e349abd..e87f15ca 100644
--- a/partitura/io/exportmusicxml.py
+++ b/partitura/io/exportmusicxml.py
@@ -417,9 +417,10 @@ def linearize_segment_contents(part, start, end, state):
 
     for voice in sorted(notes_by_voice.keys()):
         voice_notes = notes_by_voice[voice]
-        # sort by pitch
+        # sort by pitch (then step in case of enharmonic notes)
         voice_notes.sort(
-            key=lambda n: n.midi_pitch if hasattr(n, "midi_pitch") else -1, reverse=True
+            key=lambda n: (n.midi_pitch, n.step) if hasattr(n, "midi_pitch") else (-1, ""),
+            reverse=True,
         )
         # grace notes should precede other notes at the same onset
         voice_notes.sort(key=lambda n: not isinstance(n, score.GraceNote))