diff --git a/include/event2/thread.h b/include/event2/thread.h
index f49dd27a..9802e0ae 100644
--- a/include/event2/thread.h
+++ b/include/event2/thread.h
@@ -67,7 +67,7 @@ extern "C" {
 
    @return the number of locks required by libevent
 */
-int evthread_num_locks();
+int evthread_num_locks(void);
 
 struct event_base;
 /**
diff --git a/test/regress_pthread.c b/test/regress_pthread.c
index 52d7e100..cda86997 100644
--- a/test/regress_pthread.c
+++ b/test/regress_pthread.c
@@ -42,6 +42,8 @@
 
 static pthread_mutex_t *all_locks;
 
+void regress_pthread(void);
+
 struct cond_wait {
 	pthread_mutex_t lock;
 	pthread_cond_t cond;
@@ -146,7 +148,7 @@ get_id(void)
 }
 
 void
-regress_pthread()
+regress_pthread(void)
 {
 	struct event_base *base = event_base_new();
 	int i;