diff --git a/audio/libao/Makefile b/audio/libao/Makefile
index aaed0cd66781..0d0f04a723a3 100644
--- a/audio/libao/Makefile
+++ b/audio/libao/Makefile
@@ -7,7 +7,7 @@
 
 PORTNAME=	libao
 PORTVERSION=	0.8.5
-PORTREVISION=	3
+PORTREVISION=	4
 CATEGORIES=	audio
 MASTER_SITES=	http://www.xiph.org/ao/src/
 
diff --git a/audio/libao/files/patch-include_ao_ao.h b/audio/libao/files/patch-include_ao_ao.h
new file mode 100644
index 000000000000..7295a654dea2
--- /dev/null
+++ b/audio/libao/files/patch-include_ao_ao.h
@@ -0,0 +1,14 @@
+
+$FreeBSD$
+
+--- include/ao/ao.h.orig
++++ include/ao/ao.h
+@@ -134,7 +134,7 @@
+ 
+ /* driver information */
+ int ao_driver_id(const char *short_name);
+-int ao_default_driver_id();
++int ao_default_driver_id(void);
+ ao_info *ao_driver_info(int driver_id);
+ ao_info **ao_driver_info_list(int *driver_count);
+ char *ao_file_extension(int driver_id);