Index: openacs-4/packages/xowiki/tcl/includelet-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xowiki/tcl/includelet-procs.tcl,v
diff -u -r1.239.2.17 -r1.239.2.18
--- openacs-4/packages/xowiki/tcl/includelet-procs.tcl	31 Aug 2019 08:46:07 -0000	1.239.2.17
+++ openacs-4/packages/xowiki/tcl/includelet-procs.tcl	2 Sep 2019 17:00:08 -0000	1.239.2.18
@@ -4603,7 +4603,7 @@
         }}
       }
 
-  gravatar proc url {-email {-size 80}} {
+  gravatar proc url {-email {-size 80} {-default mp}} {
     # reusable helper proc to compute a gravatar URL
     if {[info commands ns_md5] ne ""} {
       set md5 [string tolower [ns_md5 $email]]
@@ -4612,7 +4612,7 @@
       set md5 [string tolower [md5::Hex [md5::md5 -- $email]]]
     }
     security::csp::require img-src www.gravatar.com
-    return //www.gravatar.com/avatar/$md5?size=$size
+    return //www.gravatar.com/avatar/$md5?size=$size&d=$default
   }
 
   gravatar instproc render {} {