--- gegl-0.0.22/gegl/property-types/gegl-path.c.old	2009-02-24 17:27:52.615641000 +0800
+++ gegl-0.0.22/gegl/property-types/gegl-path.c	2009-02-24 17:27:38.830330000 +0800
@@ -1458,6 +1458,8 @@
   GeglPathList *prev = NULL;
   InstructionInfo *info = lookup_instruction_info (knot->type);
 
+  if (info != NULL)
+    {
   gint count=0;
   for (iter = priv->path; iter; iter=iter->next)
     {
@@ -1492,6 +1494,7 @@
   priv->flat_path_clean = FALSE;
   priv->length_clean = FALSE;
   gegl_path_emit_changed (vector, NULL);
+    }
 }
 
 void  gegl_path_replace_node (GeglPath           *vector,