diff --git a/transport.c b/transport.c
index 393e0e8fe233ca51dc4c5db94c55e81ee53baa52..a3b805258f2d1403f6b5de96f94738f2337f0627 100644
--- a/transport.c
+++ b/transport.c
@@ -203,7 +203,7 @@ static struct ref *get_refs_via_rsync(struct transport *transport)
 }
 
 static int fetch_objs_via_rsync(struct transport *transport,
-				 int nr_objs, struct ref **to_fetch)
+				int nr_objs, const struct ref **to_fetch)
 {
 	struct strbuf buf = STRBUF_INIT;
 	struct child_process rsync;
@@ -350,7 +350,7 @@ static int rsync_transport_push(struct transport *transport,
 
 #ifndef NO_CURL /* http fetch is the only user */
 static int fetch_objs_via_walker(struct transport *transport,
-				 int nr_objs, struct ref **to_fetch)
+				 int nr_objs, const struct ref **to_fetch)
 {
 	char *dest = xstrdup(transport->url);
 	struct walker *walker = transport->data;
@@ -504,7 +504,7 @@ static struct ref *get_refs_via_curl(struct transport *transport)
 }
 
 static int fetch_objs_via_curl(struct transport *transport,
-				 int nr_objs, struct ref **to_fetch)
+				 int nr_objs, const struct ref **to_fetch)
 {
 	if (!transport->data)
 		transport->data = get_http_walker(transport->url,
@@ -542,7 +542,7 @@ static struct ref *get_refs_from_bundle(struct transport *transport)
 }
 
 static int fetch_refs_from_bundle(struct transport *transport,
-			       int nr_heads, struct ref **to_fetch)
+			       int nr_heads, const struct ref **to_fetch)
 {
 	struct bundle_transport_data *data = transport->data;
 	return unbundle(&data->header, data->fd);
@@ -616,7 +616,7 @@ static struct ref *get_refs_via_connect(struct transport *transport)
 }
 
 static int fetch_refs_via_pack(struct transport *transport,
-			       int nr_heads, struct ref **to_fetch)
+			       int nr_heads, const struct ref **to_fetch)
 {
 	struct git_transport_data *data = transport->data;
 	char **heads = xmalloc(nr_heads * sizeof(*heads));
@@ -784,12 +784,12 @@ const struct ref *transport_get_remote_refs(struct transport *transport)
 	return transport->remote_refs;
 }
 
-int transport_fetch_refs(struct transport *transport, struct ref *refs)
+int transport_fetch_refs(struct transport *transport, const struct ref *refs)
 {
 	int rc;
 	int nr_heads = 0, nr_alloc = 0;
-	struct ref **heads = NULL;
-	struct ref *rm;
+	const struct ref **heads = NULL;
+	const struct ref *rm;
 
 	for (rm = refs; rm; rm = rm->next) {
 		if (rm->peer_ref &&
diff --git a/transport.h b/transport.h
index 8abfc0ae60c18165b44ef93ed9115972b991e2dc..d0b52053fff9bc463438674232bffb6024f3b1fc 100644
--- a/transport.h
+++ b/transport.h
@@ -19,7 +19,7 @@ struct transport {
 			  const char *value);
 
 	struct ref *(*get_refs_list)(struct transport *transport);
-	int (*fetch)(struct transport *transport, int refs_nr, struct ref **refs);
+	int (*fetch)(struct transport *transport, int refs_nr, const struct ref **refs);
 	int (*push)(struct transport *connection, int refspec_nr, const char **refspec, int flags);
 
 	int (*disconnect)(struct transport *connection);
@@ -68,7 +68,7 @@ int transport_push(struct transport *connection,
 
 const struct ref *transport_get_remote_refs(struct transport *transport);
 
-int transport_fetch_refs(struct transport *transport, struct ref *refs);
+int transport_fetch_refs(struct transport *transport, const struct ref *refs);
 void transport_unlock_pack(struct transport *transport);
 int transport_disconnect(struct transport *transport);