diff --git a/include/osmocom/core/timer.h b/include/osmocom/core/timer.h
index db2ecbf..6c2e8c5 100644
--- a/include/osmocom/core/timer.h
+++ b/include/osmocom/core/timer.h
@@ -64,9 +64,9 @@
 /**
  * internal timer list management
  */
-struct timeval *osmo_timers_nearest();
-void osmo_timers_prepare();
-int osmo_timers_update();
+struct timeval *osmo_timers_nearest(void);
+void osmo_timers_prepare(void);
+int osmo_timers_update(void);
 int osmo_timers_check(void);
 
 #endif
diff --git a/src/timer.c b/src/timer.c
index ec75212..bd11a46 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -80,7 +80,7 @@
  * If the nearest timer timed out return NULL and then we will
  * dispatch everything after the select
  */
-struct timeval *osmo_timers_nearest()
+struct timeval *osmo_timers_nearest(void)
 {
 	struct timeval current_time;
 
@@ -107,7 +107,7 @@
 /*
  * Find the nearest time and update s_nearest_time
  */
-void osmo_timers_prepare()
+void osmo_timers_prepare(void)
 {
 	struct osmo_timer_list *timer, *nearest_timer = NULL;
 	llist_for_each_entry(timer, &timer_list, entry) {
@@ -126,7 +126,7 @@
 /*
  * fire all timers... and remove them
  */
-int osmo_timers_update()
+int osmo_timers_update(void)
 {
 	struct timeval current_time;
 	struct osmo_timer_list *timer, *tmp;