diff --git a/tests/mgcp/mgcp_test.c b/tests/mgcp/mgcp_test.c
index d843d10..2d8dfec 100644
--- a/tests/mgcp/mgcp_test.c
+++ b/tests/mgcp/mgcp_test.c
@@ -2078,7 +2078,7 @@
 	OSMO_ASSERT(ok);
 }
 
-void test_conn_id_matching()
+void test_conn_id_matching(void)
 {
 	struct mgcp_endpoint endp = {};
 	struct mgcp_conn *conn;
@@ -2118,7 +2118,7 @@
 	talloc_free(conn);
 }
 
-void test_e1_trunk_nr_from_epname()
+void test_e1_trunk_nr_from_epname(void)
 {
 	unsigned int trunk_nr;
 	int rc;
@@ -2168,7 +2168,7 @@
 	return;
 }
 
-void test_mgcp_is_rtp_dummy_payload()
+void test_mgcp_is_rtp_dummy_payload(void)
 {
 	/* realistic rtp packet */
 	static const char rtp_payload[] =