diff --git a/gc-notes.txt b/gc-notes.txt
index ad2de7a3..638af854 100644
--- a/gc-notes.txt
+++ b/gc-notes.txt
@@ -14,7 +14,8 @@ TODO:
   part of this is implementing the beginnings of srfi-18, to create multiple threads, sync them, etc
   next steps:
   - add mutex type, and associated functions from SRFI-18
-  - break out srfi 18 stuff into a (scheme srfi 18) module, or such
+    when allocating a mutex, probably should do it on thread since by definition these are
+    shared among multiple threads
   - start making core stuff thread safe. for example, test.scm sometimes
     crashes, I think printing out result from (read)
   - assume I/O and eval both have threading issues