diff --git a/src/decoder/plugins/FfmpegIo.hxx b/src/decoder/plugins/FfmpegIo.hxx
--- a/src/decoder/plugins/FfmpegIo.hxx
+++ b/src/decoder/plugins/FfmpegIo.hxx
@@ -22,6 +22,7 @@
 
 extern "C" {
 #include "libavformat/avio.h"
+#include "libavutil/mem.h"
 }
 
 #include <cstdint>

.