diff --git a/collects/teachpack/2htdp/scribblings/batch-io.scrbl b/collects/teachpack/2htdp/scribblings/batch-io.scrbl
index 272e929fa1..11ecdda6b4 100644
--- a/collects/teachpack/2htdp/scribblings/batch-io.scrbl
+++ b/collects/teachpack/2htdp/scribblings/batch-io.scrbl
@@ -139,3 +139,5 @@ There is only one writer function at the moment:
 }
 ]
 
+@(delete-file "output.txt")
+
diff --git a/src/mzscheme/src/places.c b/src/mzscheme/src/places.c
index 98bfb012b7..bdfcc6ff86 100644
--- a/src/mzscheme/src/places.c
+++ b/src/mzscheme/src/places.c
@@ -36,6 +36,7 @@ static void register_traversers(void);
 # endif
 
 static void *place_start_proc(void *arg);
+static void *place_start_proc_after_stack(void *data_arg, void *stack_base);
 
 # define PLACE_PRIM_W_ARITY(name, func, a1, a2, env) GLOBAL_PRIM_W_ARITY(name, func, a1, a2, env)
 
@@ -608,6 +609,14 @@ Scheme_Struct_Type *scheme_make_prefab_struct_type_in_master(Scheme_Object *base
 
 static void *place_start_proc(void *data_arg) {
   void *stack_base;
+  void *rc;
+  stack_base = PROMPT_STACK(stack_base);
+  rc = place_start_proc_after_stack(data_arg, stack_base);
+  stack_base = NULL;
+  return rc;
+}
+  
+static void *place_start_proc_after_stack(void *data_arg, void *stack_base) {
   Place_Start_Data *place_data;
   Scheme_Object *place_main;
   Scheme_Object *a[2], *channel;
@@ -615,7 +624,6 @@ static void *place_start_proc(void *data_arg) {
   long rc = 0;
   ptid = mz_proc_thread_self();
   
-  stack_base = PROMPT_STACK(stack_base);
   place_data = (Place_Start_Data *) data_arg;
   data_arg = NULL;