diff --git a/TODO.md b/TODO.md
index 62364e065..94e7f8df6 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,6 @@
 # to-do for 0.6pre1
 
+- fix an OPLL/OPL fixed drum freq regression caused by full linear pitch
 - piano/input pad
   - note input via piano
   - input pad