diff --git a/gc.c b/gc.c
index 8e40cb17..ede7cf46 100644
--- a/gc.c
+++ b/gc.c
@@ -1242,6 +1242,10 @@ void gc_thread_data_free(gc_thread_data *thd)
   }
 }
 
+/**
+ * Called explicitly from a mutator thread to let the collector know
+ * it (may) block for an unknown period of time.
+ */
 void gc_mutator_thread_blocked(gc_thread_data *thd, object cont)
 {
   if(!ck_pr_cas_int((int *)&(thd->thread_state), 
@@ -1254,8 +1258,15 @@ void gc_mutator_thread_blocked(gc_thread_data *thd, object cont)
   thd->gc_num_args = 0; // Will be set later, after collection
 }
 
+/**
+ * Called explicitly from a mutator thread to let the collector know
+ * that it has finished blocking. In addition, if the collector 
+ * cooperated on behalf of the mutator while it was blocking, the mutator
+ * will move any remaining stack objects to the heap and longjmp.
+ */
 void gc_mutator_thread_runnable(gc_thread_data *thd, object result)
 {
+  char stack_limit;
   // Transition from blocked back to runnable using CAS.
   // If we are unable to transition back, assume collector
   // has cooperated on behalf of this mutator thread.
@@ -1274,7 +1285,7 @@ void gc_mutator_thread_runnable(gc_thread_data *thd, object result)
     thd->gc_args[0] = result;
     thd->gc_num_args = 1;
     // Move any remaining stack objects (should only be the result?) to heap
-    gc_minor(thd, thd->stack_limit, thd->stack_start, thd->gc_cont, thd->gc_args, thd->gc_num_args);
+    gc_minor(thd, &stack_limit, thd->stack_start, thd->gc_cont, thd->gc_args, thd->gc_num_args);
 //printf("DEBUG - Call into gc_cont after collector coop\n");
     // Whoa.
     longjmp(*(thd->jmp_start), 1);
diff --git a/runtime.c b/runtime.c
index 266de942..39935119 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2337,7 +2337,7 @@ char *gc_move(char *obj, gc_thread_data *thd, int *alloci, int *heap_grown) {
 
 object Cyc_trigger_minor_gc(void *data, object cont) {
   gc_thread_data* thd = (gc_thread_data *)data;
-  thd->gc_args = boolean_t;
+  thd->gc_args[0] = boolean_t;
   GC(data, cont, thd->gc_args, 1);
   return nil;
 }