--- a\src\iup_childtree.c	Tue May 02 23:06:40 2017
+++ b\src\iup_childtree.c	Fri Jan 19 00:10:02 2018
@@ -440,7 +440,7 @@
 
   iupASSERT(iupObjectCheck(ih));
   if (!iupObjectCheck(ih))
-    return -1;
+    return 0;
 
   for (child = ih->firstchild; child; child = child->brother)
     count++;