Index: generic/gentclAPI.tcl
===================================================================
diff -u -rdb9cc86bb6df8dadf59f951a504c908fb8d14ef0 -r4182e5c48847acdfdb384d0ab998f453e1434c69
--- generic/gentclAPI.tcl	(.../gentclAPI.tcl)	(revision db9cc86bb6df8dadf59f951a504c908fb8d14ef0)
+++ generic/gentclAPI.tcl	(.../gentclAPI.tcl)	(revision 4182e5c48847acdfdb384d0ab998f453e1434c69)
@@ -76,7 +76,11 @@
 #     }
     lappend l "{\"$argName\", $flags, $(-nrargs), ConvertTo$converter}"
   }
-  join $l ",\n  "
+  if {[llength $l] == 0} {
+    return "{NULL, 0, 0, NULL}"
+  } else {
+    return [join $l ",\n  "]
+  }
 }
 
 proc gencall {fn parameterDefinitions clientData cDefsVar ifDefVar arglistVar preVar postVar introVar} {