diff --git a/runtime.c b/runtime.c
index 21bf948d..d695abbe 100644
--- a/runtime.c
+++ b/runtime.c
@@ -3157,6 +3157,19 @@ object Cyc_spawn_thread(object thunk)
 // here. will need to pass it, along with thunk, to Cyc_init_thread.
 // Then can use a new function up there to add the mutator, since we
 // already have the number.
+/*
+how to manage gc mutators. need to handle:
+- need to be able to allocate a thread but not run it yet.
+  maybe have a run level, or status
+- need to make mutators thread safe, ideally without major performance impacts
+- thread terminates
+  - should mark mutator as 'done'
+  - at an opportune moment, free mutator and set it back
+    to null
+
+what is the right data structure? is the array OK? or would it be better
+to look at the lock-free structures provided by ck?
+*/
   pthread_t thread;
   pthread_attr_t attr;
   pthread_attr_init(&attr);