diff --git a/libavformat/mxfenc.c b/libavformat/mxfenc.c
index 6c82339e7d..d5e4ecf9e9 100644
--- a/libavformat/mxfenc.c
+++ b/libavformat/mxfenc.c
@@ -77,7 +77,7 @@ typedef struct {
     UID container_ul;
     UID element_ul;
     UID codec_ul;
-    void (*write_desc)();
+    void (*write_desc)(AVFormatContext *, AVStream *);
 } MXFContainerEssenceEntry;
 
 static const struct {