diff --git a/source/compiler/sc3.c b/source/compiler/sc3.c
index c3d9584..af3f2b8 100644
--- a/source/compiler/sc3.c
+++ b/source/compiler/sc3.c
@@ -2274,7 +2274,8 @@ static int nesting=0;
           check_tagmismatch_multiple(arg[argidx].tags,arg[argidx].numtags,lval.tag,-1);
           if (lval.tag!=0)
             append_constval(&taglst,arg[argidx].name,lval.tag,0);
-          // ??? set uWRITTEN?
+          if (lval.sym!=NULL && (arg[argidx].usage & uCONST)==0)
+            markusage(lval.sym,uWRITTEN);
           argidx++;               /* argument done */
           break;
         } /* switch */