diff --git a/gcc/d/d-attribs.cc b/gcc/d/d-attribs.cc
index d81b7d122f7..1ec800526f7 100644
--- a/gcc/d/d-attribs.cc
+++ b/gcc/d/d-attribs.cc
@@ -852,7 +852,9 @@ parse_optimize_options (tree args)
   unsigned j = 1;
   for (unsigned i = 1; i < decoded_options_count; ++i)
     {
-      if (! (cl_options[decoded_options[i].opt_index].flags & CL_OPTIMIZATION))
+      unsigned opt_index = decoded_options[i].opt_index;
+      if (opt_index >= cl_options_count
+	  && ! (cl_options[opt_index].flags & CL_OPTIMIZATION))
 	{
 	  ret = false;
 	  warning (OPT_Wattributes,