diff --git a/.gdbinit b/.gdbinit
index 4a544f08ee..b4db0714e7 100644
--- a/.gdbinit
+++ b/.gdbinit
@@ -861,7 +861,7 @@ end
 
 define nd_tree
   set $buf = (struct RString *)rb_str_buf_new(0)
-  call dump_node((VALUE)($buf), rb_str_new(0, 0), 0, ($arg0))
+  call dump_node((VALUE)($buf), rb_str_tmp_new(0), 0, ($arg0))
   printf "%s\n", $buf->as.heap.ptr
 end