diff --git a/data/midi-to-encoding.py b/data/midi-to-encoding.py
index e7eb0863..3140c29a 100755
--- a/data/midi-to-encoding.py
+++ b/data/midi-to-encoding.py
@@ -47,7 +47,7 @@ def stream_to_chordwise(s, chamber, note_range, note_offset, sample_freq):
     for c in s.recurse().addFilter(chordFilter):
         pitchesInChord=c.pitches
         if chamber:
-            instrumentID=assign_instrument(n.activeSite.getInstrument())     
+            instrumentID=assign_instrument(c.activeSite.getInstrument())     
             if instrumentID==-1:
                 return []
 
@@ -247,4 +247,4 @@ def main(chamber, composers, replace):
 
     composers=args.composers.split(",") if args.composers else []
 
-    main(args.chamber, composers, args.replace)
\ No newline at end of file
+    main(args.chamber, composers, args.replace)