diff --git a/src/virtual-output/hflip.cpp b/src/virtual-output/hflip.cpp
index 7f4303f..a40fff1 100644
--- a/src/virtual-output/hflip.cpp
+++ b/src/virtual-output/hflip.cpp
@@ -10,8 +10,8 @@ bool init_flip_filter(FlipContext* ctx,int width, int height, int format)
 
 	avfilter_register_all();
 
-	AVFilter *buffersrc = avfilter_get_by_name("buffer");
-	AVFilter *buffersink = avfilter_get_by_name("buffersink");
+	const AVFilter *buffersrc = avfilter_get_by_name("buffer");
+	const AVFilter *buffersink = avfilter_get_by_name("buffersink");
 	AVFilterInOut *outputs = avfilter_inout_alloc();
 	AVFilterInOut *inputs = avfilter_inout_alloc();
 	enum AVPixelFormat pix_fmts[] = { (AVPixelFormat)format, AV_PIX_FMT_NONE };
diff --git a/src/virtual-output/hflip.h b/src/virtual-output/hflip.h
index c38598d..29c712d 100644
--- a/src/virtual-output/hflip.h
+++ b/src/virtual-output/hflip.h
@@ -1,7 +1,6 @@
 extern "C"
 {
 #include "stdint.h"
-#include "libavfilter/avfiltergraph.h"  
 #include "libavfilter/buffersink.h"  
 #include "libavfilter/buffersrc.h"  
 #include "libavutil/avutil.h"