diff --git a/openbsc/src/gprs/gprs_utils.c b/openbsc/src/gprs/gprs_utils.c
index 55d4efd..c620454 100644
--- a/openbsc/src/gprs/gprs_utils.c
+++ b/openbsc/src/gprs/gprs_utils.c
@@ -47,21 +47,29 @@
 	new_msg->head += msg->head - msg->_data;
 	new_msg->tail += msg->tail - msg->_data;
 
-	new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
-	new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
-	new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
-	new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);
+	if (msg->l1h)
+		new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
+	if (msg->l2h)
+		new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
+	if (msg->l3h)
+		new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
+	if (msg->l4h)
+		new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);
 
 	/* copy GB specific data */
 	old_cb = LIBGB_MSGB_CB(msg);
 	new_cb = LIBGB_MSGB_CB(new_msg);
 
-	new_cb->bssgph = new_msg->_data + (old_cb->bssgph - msg->_data);
-	new_cb->llch = new_msg->_data + (old_cb->llch - msg->_data);
+	if (old_cb->bssgph)
+		new_cb->bssgph = new_msg->_data + (old_cb->bssgph - msg->_data);
+	if (old_cb->llch)
+		new_cb->llch = new_msg->_data + (old_cb->llch - msg->_data);
 
 	/* bssgp_cell_id is a pointer into the old msgb, so we need to make
 	 * it a pointer into the new msgb */
-	new_cb->bssgp_cell_id = new_msg->_data + (old_cb->bssgp_cell_id - msg->_data);
+	if (old_cb->bssgp_cell_id)
+		new_cb->bssgp_cell_id = new_msg->_data +
+			(old_cb->bssgp_cell_id - msg->_data);
 	new_cb->nsei = old_cb->nsei;
 	new_cb->bvci = old_cb->bvci;
 	new_cb->tlli = old_cb->tlli;