diff --git a/preprocessor/macro/MacroBison.yy b/preprocessor/macro/MacroBison.yy
index 27c0e4b28c11dc61735eee686730545d698b054e..0a9269b4511958d9cb9a4363a65a3c708ec2e2f2 100644
--- a/preprocessor/macro/MacroBison.yy
+++ b/preprocessor/macro/MacroBison.yy
@@ -139,7 +139,7 @@ expr : INTEGER
            }
          delete $1;
        }
-     | LENGTH LPAREN array_expr RPAREN
+     | LENGTH LPAREN expr RPAREN
        { TYPERR_CATCH($$ = $3->length(), @$); }
      | LPAREN expr RPAREN
        { $$ = $2; }