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"