diff --git a/gbproxy/GBProxy_Tests.ttcn b/gbproxy/GBProxy_Tests.ttcn
index 5bb77d3..30a019e 100644
--- a/gbproxy/GBProxy_Tests.ttcn
+++ b/gbproxy/GBProxy_Tests.ttcn
@@ -289,6 +289,15 @@
         return ret;
 };
 
+private function f_fix_create_cb(inout BssgpConfig cfg)
+{
+	for (var integer i := 0; i < lengthof(cfg.bvc); i := i + 1) {
+		if (not isbound(cfg.bvc[i].create_cb)) {
+			cfg.bvc[i].create_cb := refers(BSSGP_Emulation.DefaultCreateCallback)
+		}
+	}
+}
+
 private function f_init_gb_pcu(inout GbInstance gb, charstring id, integer offset) runs on test_CT {
 	var charstring ns_id := id & "-NS(PCU[" & int2str(offset) & "])";
 	var charstring bssgp_id := id & "-BSSGP(PCU[" & int2str(offset) & "])";
@@ -364,8 +373,10 @@
 	}
 	for (i := 0; i < lengthof(mp_gbconfigs); i := i+1) {
 		g_pcu[i].cfg := mp_gbconfigs[i];
+		/* make sure all have a proper crate_cb, which cannot be specified in config file */
+		f_fix_create_cb(g_pcu[i].cfg);
 		/* concatenate all the PCU-side BVCs for the SGSN side */
-		g_sgsn[0].cfg.bvc := g_sgsn[0].cfg.bvc & mp_gbconfigs[i].bvc;
+		g_sgsn[0].cfg.bvc := g_sgsn[0].cfg.bvc & g_pcu[i].cfg.bvc;
 	}
 
 	f_init_vty();