--- a/netconf/src/ncx/val.c
+++ b/netconf/src/ncx/val.c
@@ -3685,7 +3685,7 @@
     size_t buf_len;
 } serializer_node_t;
 
-static ssize_t writer_fn(void *cookie, const void *buffer, size_t size)
+static int writer_fn(void *cookie, const char *buffer, int size)
 {
     serializer_node_t* ser = (serializer_node_t *)cookie;
 
@@ -3717,15 +3717,9 @@
     serializer_node_t ser;
     status_t res;
     FILE* fp;
-    cookie_io_functions_t io_functions;
     val_value_t* copy_val;
 
-    io_functions.read=NULL;
-    io_functions.write=(cookie_write_function_t *)writer_fn;
-    io_functions.seek=NULL;
-    io_functions.close=NULL;
-
-    fp=fopencookie (&ser, "w", io_functions);
+    fp=fwopen (&ser, writer_fn);
     assert(fp != NULL);
 
     ser.buf=NULL;
@@ -3747,7 +3741,7 @@
     }
     fclose(fp);
 
-    fp=fopencookie (&ser, "w", io_functions);
+    fp=fwopen (&ser, writer_fn);
     assert(fp != NULL);
 
     ser.buf=(char*)malloc(ser.buf_len+1);