Index: trunk/src/layer.c
===================================================================
--- trunk/src/layer.c	(revision 12093)
+++ trunk/src/layer.c	(revision 12094)
@@ -207,8 +207,14 @@
 
 	/* bound layer: if it is already bound to a real layer, use that, whatever it is (manual binding may override our local type match pattern) */
 	if (layer->meta.bound.real != NULL) {
-		layer = layer->meta.bound.real;
-		assert(!layer->is_bound);
+		int rec = 0;
+		while(layer->is_bound) {
+			layer = layer->meta.bound.real;
+			rec++;
+			if ((rec > PCB_MAX_BOUND_LAYER_RECURSION) || (layer == 0))
+				return 0;
+		}
+
 		return pcb_layer_flags_(layer); /* tail recursion */
 	}
 
Index: trunk/src/layer.h
===================================================================
--- trunk/src/layer.h	(revision 12093)
+++ trunk/src/layer.h	(revision 12094)
@@ -28,6 +28,9 @@
 #ifndef PCB_LAYER_H
 #define PCB_LAYER_H
 
+/* How deep subcs can be nested */
+#define PCB_MAX_BOUND_LAYER_RECURSION 128
+
 typedef long int pcb_layer_id_t;
 typedef long int pcb_layergrp_id_t;