diff --git a/include/osmocom/core/counter.h b/include/osmocom/core/counter.h
index 0d56bc4..7b677cb 100644
--- a/include/osmocom/core/counter.h
+++ b/include/osmocom/core/counter.h
@@ -52,7 +52,7 @@
 
 int osmo_counters_for_each(int (*handle_counter)(struct osmo_counter *, void *), void *data);
 
-int osmo_counters_count();
+int osmo_counters_count(void);
 
 struct osmo_counter *osmo_counter_get_by_name(const char *name);
 
diff --git a/include/osmocom/core/select.h b/include/osmocom/core/select.h
index e9f19a5..fc14851 100644
--- a/include/osmocom/core/select.h
+++ b/include/osmocom/core/select.h
@@ -105,8 +105,8 @@
 struct osmo_signalfd *
 osmo_signalfd_setup(void *ctx, sigset_t set, osmo_signalfd_cb *cb, void *data);
 
-void osmo_select_shutdown_request();
-int osmo_select_shutdown_requested();
-bool osmo_select_shutdown_done();
+void osmo_select_shutdown_request(void);
+int osmo_select_shutdown_requested(void);
+bool osmo_select_shutdown_done(void);
 
 /*! @} */
diff --git a/include/osmocom/gprs/gprs_bssgp.h b/include/osmocom/gprs/gprs_bssgp.h
index 09f640d..6c04332 100644
--- a/include/osmocom/gprs/gprs_bssgp.h
+++ b/include/osmocom/gprs/gprs_bssgp.h
@@ -235,7 +235,7 @@
 int bssgp_fc_ms_init(struct bssgp_flow_control *fc_ms, uint16_t bvci,
 		     uint16_t nsei, uint32_t max_queue_depth);
 
-void bssgp_flush_all_queues();
+void bssgp_flush_all_queues(void);
 void bssgp_fc_flush_queue(struct bssgp_flow_control *fc);
 
 /* gprs_bssgp_vty.c */
diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index b4c7803..dcff415 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -73,7 +73,7 @@
 struct msgb *gsm0808_create_cipher_complete(struct msgb *layer3, uint8_t alg_id);
 struct msgb *gsm0808_create_cipher_reject(enum gsm0808_cause cause);
 struct msgb *gsm0808_create_cipher_reject_ext(enum gsm0808_cause_class class, uint8_t ext);
-struct msgb *gsm0808_create_classmark_request();
+struct msgb *gsm0808_create_classmark_request(void);
 struct msgb *gsm0808_create_classmark_update(const uint8_t *cm2, uint8_t cm2_len,
 					     const uint8_t *cm3, uint8_t cm3_len);
 struct msgb *gsm0808_create_sapi_reject_cause(uint8_t link_id, uint16_t cause);
@@ -269,8 +269,8 @@
 };
 struct msgb *gsm0808_create_handover_command(const struct gsm0808_handover_command *params);
 
-struct msgb *gsm0808_create_handover_detect();
-struct msgb *gsm0808_create_handover_succeeded();
+struct msgb *gsm0808_create_handover_detect(void);
+struct msgb *gsm0808_create_handover_succeeded(void);
 
 struct gsm0808_handover_complete {
 	bool rr_cause_present;
diff --git a/include/osmocom/vty/command.h b/include/osmocom/vty/command.h
index e3919fb..61b5881 100644
--- a/include/osmocom/vty/command.h
+++ b/include/osmocom/vty/command.h
@@ -442,8 +442,8 @@
 vector cmd_make_strvec(const char *);
 int cmd_make_strvec2(const char *string, char **indent, vector *strvec_p);
 void cmd_free_strvec(vector);
-vector cmd_describe_command();
-char **cmd_complete_command();
+vector cmd_describe_command(vector vline, struct vty *vty, int *status);
+char **cmd_complete_command(vector vline, struct vty *vty, int *status);
 const char *cmd_prompt(enum node_type);
 int config_from_file(struct vty *, FILE *);
 enum node_type node_parent(enum node_type);
diff --git a/include/osmocom/vty/logging.h b/include/osmocom/vty/logging.h
index 90c8fa1..0ea6432 100644
--- a/include/osmocom/vty/logging.h
+++ b/include/osmocom/vty/logging.h
@@ -6,7 +6,7 @@
 #define FILTER_STR	"Filter log messages\n"
 
 struct log_info;
-void logging_vty_add_cmds();
+void logging_vty_add_cmds(void);
 void logging_vty_add_deprecated_subsys(void *ctx, const char *name);
 struct vty;
 struct log_target *osmo_log_vty2tgt(struct vty *vty);