--- loncom/xml/run.pm	2019/11/10 20:40:59	1.65
+++ loncom/xml/run.pm	2020/03/12 20:20:13	1.66
@@ -1,6 +1,6 @@
 package Apache::run;
 #
-# $Id: run.pm,v 1.65 2019/11/10 20:40:59 raeburn Exp $
+# $Id: run.pm,v 1.66 2020/03/12 20:20:13 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -41,7 +41,7 @@ while (!$_LONCAPA_INTERNAL_oldexpression
              #             or  hash dereferences {}
              # the ^$ and ^& is because we do this iteratively
              #    $a[$c] becomes $a[3] which then evaluates
-             ([\[\{][^\$\&\]\}]+[\]\}])*?
+             ((?:[\[\{][^\$\&\]\}]+[\]\}])+|)
              # $3 is the list of arguments
              (\([^\$\&\)]+\))*?
                 # only match the above if there is not { [ ( coming up