diff --git a/libmpdemux/muxer.h b/libmpdemux/muxer.h
index 6770e5d85f..aa862f9267 100644
--- a/libmpdemux/muxer.h
+++ b/libmpdemux/muxer.h
@@ -98,6 +98,8 @@ typedef struct muxbuf_t {
   unsigned int flags;
 } muxbuf_t;
 
+extern char *force_fourcc;
+
 muxer_t *muxer_new_muxer(int type,stream_t *stream);
 #define muxer_new_stream(muxer,a) muxer->cont_new_stream(muxer,a)
 #define muxer_stream_fix_parameters(muxer, a) muxer->fix_stream_parameters(a)
diff --git a/libmpdemux/muxer_lavf.c b/libmpdemux/muxer_lavf.c
index f9531a35a8..3067d78417 100644
--- a/libmpdemux/muxer_lavf.c
+++ b/libmpdemux/muxer_lavf.c
@@ -239,7 +239,7 @@ static void fix_parameters(muxer_stream_t *stream)
 	else if(stream->type == MUXER_TYPE_VIDEO)
 	{
 		ctx->codec_id = codec_get_bmp_id(stream->bih->biCompression);
-                if(ctx->codec_id <= 0)
+                if(ctx->codec_id <= 0 || force_fourcc)
                     ctx->codec_tag= stream->bih->biCompression;
 		mp_msg(MSGT_MUXER, MSGL_INFO, "VIDEO CODEC ID: %d\n", ctx->codec_id);
 		ctx->width = stream->bih->biWidth;