diff --git a/include/osmocom/mgcp/mgcp_network.h b/include/osmocom/mgcp/mgcp_network.h
index 0487b91..1ed00e4 100644
--- a/include/osmocom/mgcp/mgcp_network.h
+++ b/include/osmocom/mgcp/mgcp_network.h
@@ -152,7 +152,7 @@
 int mgcp_bind_net_rtp_port(struct mgcp_endpoint *endp, int rtp_port,
 			   struct mgcp_conn_rtp *conn);
 void mgcp_free_rtp_port(struct mgcp_rtp_end *end);
-void mgcp_patch_and_count(struct mgcp_endpoint *endp,
+void mgcp_patch_and_count(const struct mgcp_endpoint *endp,
 			  struct mgcp_rtp_state *state,
 			  struct mgcp_rtp_end *rtp_end,
 			  struct osmo_sockaddr *addr, struct msgb *msg);
@@ -172,6 +172,6 @@
 					  struct mgcp_conn_rtp *conn);
 
 /* internal RTP Annex A counting */
-void mgcp_rtp_annex_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *state,
+void mgcp_rtp_annex_count(const struct mgcp_endpoint *endp, struct mgcp_rtp_state *state,
 			const uint16_t seq, const int32_t transit,
 			const uint32_t ssrc);
diff --git a/include/osmocom/mgcp/mgcp_protocol.h b/include/osmocom/mgcp/mgcp_protocol.h
index abd264c..edd0554 100644
--- a/include/osmocom/mgcp/mgcp_protocol.h
+++ b/include/osmocom/mgcp/mgcp_protocol.h
@@ -23,5 +23,5 @@
 void mgcp_rtp_end_config(struct mgcp_endpoint *endp, int expect_ssrc_change,
 			 struct mgcp_rtp_end *rtp);
 
-uint32_t mgcp_rtp_packet_duration(struct mgcp_endpoint *endp,
-				  struct mgcp_rtp_end *rtp);
+uint32_t mgcp_rtp_packet_duration(const struct mgcp_endpoint *endp,
+				  const struct mgcp_rtp_end *rtp);