Index: openacs-4/packages/forums/www/user-history.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/forums/www/user-history.tcl,v
diff -u -r1.14.2.2 -r1.14.2.3
--- openacs-4/packages/forums/www/user-history.tcl	21 May 2016 10:10:56 -0000	1.14.2.2
+++ openacs-4/packages/forums/www/user-history.tcl	11 Feb 2017 18:09:27 -0000	1.14.2.3
@@ -12,7 +12,7 @@
     {groupby "forum_name"}
 } -validate {
     valid_user -requires user_id {
-        if {![person::person_p -party_id $user_id]} {
+        if {$user_id == 0 || ![person::person_p -party_id $user_id]} {
             ad_complain "Invalid user_id"
         }
     }