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);
 
 /*! @} */