diff --git a/include/usbmuxd.h b/include/usbmuxd.h
index efda52a..cf9a1e2 100644
--- a/include/usbmuxd.h
+++ b/include/usbmuxd.h
@@ -132,7 +132,7 @@
  * @note Deprecated. Use usbmuxd_events_subscribe and usbmuxd_events_unsubscribe instead.
  * @see usbmuxd_events_unsubscribe
  */
-int usbmuxd_unsubscribe();
+int usbmuxd_unsubscribe(void);
 
 /**
  * Contacts usbmuxd and retrieves a list of connected devices.
diff --git a/src/libusbmuxd.c b/src/libusbmuxd.c
index 3987aca..4706343 100644
--- a/src/libusbmuxd.c
+++ b/src/libusbmuxd.c
@@ -1242,7 +1242,7 @@
 	return usbmuxd_events_subscribe(&event_ctx, callback, user_data);
 }
 
-USBMUXD_API int usbmuxd_unsubscribe()
+USBMUXD_API int usbmuxd_unsubscribe(void)
 {
 	int res = usbmuxd_events_unsubscribe(event_ctx);
 	event_ctx = NULL;