diff --git a/partitura/performance.py b/partitura/performance.py
index d2339ea1..fef3bbe1 100644
--- a/partitura/performance.py
+++ b/partitura/performance.py
@@ -393,6 +393,8 @@ def _validate_values(self, key=None):
                 self._validate_sound_off()
 
     def _validate_sound_off(self):
+        if self.get("note_off", -1) < 0:
+            return
         if self.pnote_dict["sound_off"] < self.pnote_dict["note_off"]:
             raise ValueError(f"sound_off must be greater or equal to note_off")