diff --git a/gc.c b/gc.c
index 04eb126a..34d27d03 100644
--- a/gc.c
+++ b/gc.c
@@ -105,6 +105,17 @@ void gc_add_mutator(gc_thread_data *thd)
   pthread_mutex_unlock(&mutators_lock);
 }
 
+void gc_remove_mutator(gc_thread_data *thd)
+{
+  pthread_mutex_lock(&mutators_lock);
+  if (!ck_array_remove(&Cyc_mutators, (void *)thd)) {
+    fprintf(stderr, "Unable to remove thread data, exiting\n");
+    exit(1);
+  }
+  ck_array_commit(&Cyc_mutators);
+  pthread_mutex_unlock(&mutators_lock);
+}
+
 gc_heap *gc_heap_create(size_t size, size_t max_size, size_t chunk_size)
 {
   gc_free_list *free, *next;
@@ -1084,7 +1095,7 @@ void gc_wait_handshake()
 {
   ck_array_iterator_t iterator;
   gc_thread_data *m;
-  int statusm, statusc;
+  int statusm, statusc, thread_status;
   struct timespec tim;
   tim.tv_sec = 0;
   tim.tv_nsec = 1000000; // 1 millisecond
@@ -1093,11 +1104,17 @@ void gc_wait_handshake()
     while (1) {
       statusc = ATOMIC_GET(&gc_status_col);
       statusm = ATOMIC_GET(&(m->gc_status));
+      thread_status = ATOMIC_GET(&(m->thread_state));
       if (statusc == statusm) {
         // Handshake succeeded, check next mutator
         break;
       }
 
+      if (thread_status == CYC_THREAD_STATE_TERMINATED) {
+        // Thread is no longer running
+        break;
+      }
+
       // At least for now, just give up quantum and come back to
       // this quickly to test again. This probably could be more
       // efficient.
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 7d3b7006..b2c23252 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -171,6 +171,7 @@ void vpbuffer_free(void **buf);
 /* GC prototypes */
 void gc_initialize();
 void gc_add_mutator(gc_thread_data *thd);
+void gc_remove_mutator(gc_thread_data *thd);
 gc_heap *gc_heap_create(size_t size, size_t max_size, size_t chunk_size);
 int gc_grow_heap(gc_heap *h, size_t size, size_t chunk_size);
 char *gc_copy_obj(object hp, char *obj, gc_thread_data *thd);
diff --git a/runtime.c b/runtime.c
index 160f8680..3d8911a6 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2493,9 +2493,6 @@ TODO: should rename this function to make it more clear what is really going on
  */
 void Cyc_start_thread(gc_thread_data *thd)
 {
-// TODO: should use an atomic set to modify this
-  thd->thread_state = CYC_THREAD_STATE_RUNNABLE;
-
   /* Tank, load the jump program... */
   setjmp(*(thd->jmp_start));
 
@@ -3211,7 +3208,12 @@ void Cyc_exit_thread(gc_thread_data *thd)
   // terminating the thread
 
 printf("DEBUG - exiting thread\n");
+// TODO: race condition, cannot free thread data if the collector is using it
+  gc_remove_mutator(thd);
   ATOMIC_SET_IF_EQ(&(thd->thread_state), CYC_THREAD_STATE_RUNNABLE, CYC_THREAD_STATE_TERMINATED);
+// TODO: could maintain a dedicated list of old thread data to clean up...
+//  collector could do it at a time that is safe
+//  gc_thread_data_free(thd);
   pthread_exit(NULL); // For now, just a proof of concept
 }