Index: hid_cam.c
===================================================================
--- hid_cam.c	(revision 28444)
+++ hid_cam.c	(revision 28445)
@@ -62,7 +62,8 @@
 	dst->fn = pcb_strdup_subst(dst->fn_template, cam_update_name_cb, &ctx, PCB_SUBST_HOME | PCB_SUBST_PERCENT | PCB_SUBST_CONF);
 }
 
-char *pcb_layer_to_file_name(gds_t *dest, pcb_layer_id_t lid, unsigned int flags, const char *purpose, int purpi, pcb_file_name_style_t style)
+
+char *pcb_layer_to_file_name_append(gds_t *dest, pcb_layer_id_t lid, unsigned int flags, const char *purpose, int purpi, pcb_file_name_style_t style)
 {
 	const pcb_virt_layer_t *v;
 	pcb_layergrp_id_t group;
@@ -73,7 +74,6 @@
 	if (flags == 0)
 		flags = pcb_layer_flags(PCB, lid);
 
-	dest->used = 0;
 
 	if (style == PCB_FNS_pcb_rnd) {
 		const char *sloc, *styp;
@@ -154,7 +154,13 @@
 	return dest->array;
 }
 
+char *pcb_layer_to_file_name(gds_t *dest, pcb_layer_id_t lid, unsigned int flags, const char *purpose, int purpi, pcb_file_name_style_t style)
+{
+	dest->used = 0;
+	return pcb_layer_to_file_name_append(dest, lid, flags, purpose, purpi, style);
+}
 
+
 char *pcb_derive_default_filename_(const char *pcbfile, const char *suffix)
 {
 	char *buf;