Index: library/nx/nx.tcl
===================================================================
diff -u -r1a67ad0bf0b5c2092e1558d13659bad489f5bb75 -rae50f752a447d5302ff8c241be8e4891ce0b4bb7
--- library/nx/nx.tcl	(.../nx.tcl)	(revision 1a67ad0bf0b5c2092e1558d13659bad489f5bb75)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision ae50f752a447d5302ff8c241be8e4891ce0b4bb7)
@@ -728,7 +728,7 @@
     :alias "info filter methods" ::nsf::cmd::ObjectInfo2::filtermethods
     :alias "info forward"        ::nsf::cmd::ObjectInfo2::forward
     :alias "info hasnamespace"   ::nsf::cmd::ObjectInfo2::hasnamespace
-    :method "info is" {kind value:optional} {::nsf::objectproperty [::nsf::current object] $kind {*}$value}
+    :method "info is" {kind value:optional} {::nsf::objectproperty [::nsf::current object] $kind {*}[expr {[info exists value]?$value:""}]}
     :alias "info methods"        ::nsf::cmd::ObjectInfo2::methods
     :alias "info mixin guard"    ::nsf::cmd::ObjectInfo2::mixinguard
     :alias "info mixin classes"  ::nsf::cmd::ObjectInfo2::mixinclasses