Index: openacs-4/packages/acs-tcl/tcl/security-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-tcl/tcl/security-procs.tcl,v
diff -u -r1.78.2.12 -r1.78.2.13
--- openacs-4/packages/acs-tcl/tcl/security-procs.tcl	30 May 2016 13:07:46 -0000	1.78.2.12
+++ openacs-4/packages/acs-tcl/tcl/security-procs.tcl	30 May 2016 13:26:02 -0000	1.78.2.13
@@ -1840,7 +1840,8 @@
     # SystemURL.
     #
     if {[util::split_location [ad_url] .proto systemHost systemPort]} {
-        if {$hostName eq $systemHost && $hostPort eq $systemPort} {
+        if {$hostName eq $systemHost
+            && ($hostPort eq $systemPort || $hostPort eq "") } {
             set $key 1
             return $host
         }