diff --git a/ChangeLog b/ChangeLog
index 359bdb72c9..21a5c985eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Wed Jan 12 19:28:23 2011  Tanaka Akira  <akr@fsij.org>
+
+	* vm.c (thread_free): reset ruby_current_thread if it points the
+	  thread to free.
+	* gc.c (slot_sweep): don't call RUBY_VM_SET_FINALIZER_INTERRUPT if
+	  there is no current thread.
+	  [ruby-dev:43000]
+
 Wed Jan 12 19:09:29 2011  Tanaka Akira  <akr@fsij.org>
 
 	* enum.c (sort_by_i): reenter check more strictly.
diff --git a/gc.c b/gc.c
index 04e87d38ef..39979138bb 100644
--- a/gc.c
+++ b/gc.c
@@ -1958,7 +1958,10 @@ slot_sweep(rb_objspace_t *objspace, struct heaps_slot *sweep_slot)
     objspace->heap.final_num += final_num;
 
     if (deferred_final_list) {
-	RUBY_VM_SET_FINALIZER_INTERRUPT(GET_THREAD());
+        rb_thread_t *th = GET_THREAD();
+        if (th) {
+            RUBY_VM_SET_FINALIZER_INTERRUPT(th);
+        }
     }
 }
 
diff --git a/vm.c b/vm.c
index f467055f92..130ca64160 100644
--- a/vm.c
+++ b/vm.c
@@ -1730,6 +1730,8 @@ thread_free(void *ptr)
 #endif
 	    ruby_xfree(ptr);
 	}
+        if (ruby_current_thread == th)
+            ruby_current_thread = NULL;
     }
     RUBY_FREE_LEAVE("thread");
 }