diff --git a/openbsc/src/gprs/sgsn_libgtp.c b/openbsc/src/gprs/sgsn_libgtp.c
index d138500..be7637a 100644
--- a/openbsc/src/gprs/sgsn_libgtp.c
+++ b/openbsc/src/gprs/sgsn_libgtp.c
@@ -358,6 +358,10 @@
 		return send_act_pdp_cont_acc(pctx);
 	}
 
+	LOGP(DGPRS, LOGL_ERROR, "Unknown ran_type %d\n",
+	     pctx->mm->ran_type);
+	reject_cause = GSM_CAUSE_PROTO_ERR_UNSPEC;
+
 reject:
 	/*
 	 * In case of a timeout pdp will be NULL but we have a valid pointer