diff --git a/ffmpegthumbnailer/libffmpegthumbnailer/pngwriter.h b/ffmpegthumbnailer/libffmpegthumbnailer/pngwriter.h

index a102e25..5f6c726 100644

--- a/ffmpegthumbnailer/libffmpegthumbnailer/pngwriter.h

+++ b/ffmpegthumbnailer/libffmpegthumbnailer/pngwriter.h

@@ -20,6 +20,7 @@

 #include <string>

 #include <vector>

 #include <png.h>

+#include <zlib.h>

 #include "imagewriter.h"