diff --git a/src/ctrl.c b/src/ctrl.c
index f101d25..11b0f5c 100644
--- a/src/ctrl.c
+++ b/src/ctrl.c
@@ -749,7 +749,7 @@
 	return 1;
 }
 
-static int hlr_ctrl_cmds_install()
+static int hlr_ctrl_cmds_install(void)
 {
 	int rc = 0;
 
diff --git a/src/dgsm.c b/src/dgsm.c
index bfa5df8..cdd82a2 100644
--- a/src/dgsm.c
+++ b/src/dgsm.c
@@ -191,7 +191,7 @@
 	dgsm_mdns_client_config_apply();
 }
 
-void dgsm_stop()
+void dgsm_stop(void)
 {
 	g_hlr->mslookup.allow_startup = false;
 	mslookup_server_mdns_config_apply();
diff --git a/src/hlr.c b/src/hlr.c
index 294da23..193dd38 100644
--- a/src/hlr.c
+++ b/src/hlr.c
@@ -568,12 +568,12 @@
 	return 0;
 }
 
-static void print_usage()
+static void print_usage(void)
 {
 	printf("Usage: osmo-hlr\n");
 }
 
-static void print_help()
+static void print_help(void)
 {
 	printf("  -h --help                  This text.\n");
 	printf("  -c --config-file filename  The config file to use.\n");
diff --git a/src/hlr_db_tool.c b/src/hlr_db_tool.c
index b2a26dc..058a12c 100644
--- a/src/hlr_db_tool.c
+++ b/src/hlr_db_tool.c
@@ -51,7 +51,7 @@
 	.db_upgrade = false,
 };
 
-static void print_help()
+static void print_help(void)
 {
 	printf("\n");
 	printf("Usage: osmo-hlr-db-tool [-l <hlr.db>] [create|import-nitb-db <nitb.db>]\n");
diff --git a/src/lu_fsm.c b/src/lu_fsm.c
index b5493db..8f02f5a 100644
--- a/src/lu_fsm.c
+++ b/src/lu_fsm.c
@@ -314,7 +314,7 @@
 	.cleanup = lu_fsm_cleanup,
 };
 
-static __attribute__((constructor)) void lu_fsm_init()
+static __attribute__((constructor)) void lu_fsm_init(void)
 {
 	OSMO_ASSERT(osmo_fsm_register(&lu_fsm) == 0);
 }
diff --git a/src/mslookup/osmo-mslookup-client.c b/src/mslookup/osmo-mslookup-client.c
index dff7d31..d2a629f 100644
--- a/src/mslookup/osmo-mslookup-client.c
+++ b/src/mslookup/osmo-mslookup-client.c
@@ -53,7 +53,7 @@
 	"\n");
 }
 
-static void print_help()
+static void print_help(void)
 {
 	print_version();
 	printf(
@@ -555,7 +555,7 @@
 	return 0;
 }
 
-void socket_close()
+void socket_close(void)
 {
 	struct socket_client *c, *n;
 	llist_for_each_entry_safe(c, n, &globals.socket_clients, entry)
diff --git a/src/mslookup_server.c b/src/mslookup_server.c
index 885adf8..3771369 100644
--- a/src/mslookup_server.c
+++ b/src/mslookup_server.c
@@ -49,7 +49,7 @@
 	result->age = age;
 }
 
-const struct mslookup_service_host *mslookup_server_get_local_gsup_addr()
+const struct mslookup_service_host *mslookup_server_get_local_gsup_addr(void)
 {
 	static struct mslookup_service_host gsup_bind = {};
 	struct mslookup_service_host *host;
diff --git a/src/mslookup_server_mdns.c b/src/mslookup_server_mdns.c
index a669526..3c7606a 100644
--- a/src/mslookup_server_mdns.c
+++ b/src/mslookup_server_mdns.c
@@ -121,7 +121,7 @@
 	talloc_free(server);
 }
 
-void mslookup_server_mdns_config_apply()
+void mslookup_server_mdns_config_apply(void)
 {
 	/* Check whether to start/stop/restart mDNS server */
 	bool should_run;