diff --git a/eval.c b/eval.c
index 8002203..b7a1789 100644
--- a/eval.c
+++ b/eval.c
@@ -12292,15 +12292,6 @@ rb_thread_start_0(fn, arg, th)
 		 "can't start a new thread (frozen ThreadGroup)");
     }
 
-
-    th->stk_start =   /* establish start of new thread's stack */
-#if STACK_GROW_DIRECTION > 0
-      (VALUE *)ruby_frame;
-#elif STACK_GROW_DIRECTION < 0
-      (VALUE *)(ruby_frame+1);
-#else
-      (VALUE *)(ruby_frame+((VALUE *)(&arg)<rb_gc_stack_start))
-#endif
  
     if (!thread_init) {
 	thread_init = 1;
@@ -12347,8 +12338,6 @@ rb_thread_start_0(fn, arg, th)
     PUSH_TAG(PROT_THREAD);
     if ((state = EXEC_TAG()) == 0) {
 	if (THREAD_SAVE_CONTEXT(th) == 0) {
-            ruby_frame->prev = top_frame;     /* hide parent thread's frames */
-            ruby_frame->tmp = 0;           
 	    curr_thread = th;
 	    th->result = (*fn)(arg, th);
 	}