Index: src/libcschem/compile.c
===================================================================
--- src/libcschem/compile.c	(revision 10332)
+++ src/libcschem/compile.c	(revision 10333)
@@ -341,7 +341,7 @@
 				long n;
 				for(n = 0; n < grp->aid.used; n++) {
 					csch_aport_t *aport = htip_get(&dst->aid2obj, grp->aid.array[n]);
-					if (aport->hdr.type == CSCH_ATYPE_PORT) {
+					if ((aport != NULL) && (aport->hdr.type == CSCH_ATYPE_PORT)) {
 						if (strcmp(aport->name, port_name) == 0)
 							return aport;
 					}