diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index b93b453e05..a2b8fa99b9 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -4312,7 +4312,6 @@ static int transcode_step(void)
 static int transcode(void)
 {
     int ret, i;
-    AVFormatContext *os;
     OutputStream *ost;
     InputStream *ist;
     int64_t timer_start;
@@ -4381,18 +4380,6 @@ static int transcode(void)
     /* dump report by using the first video and audio streams */
     print_report(1, timer_start, av_gettime_relative());
 
-    /* close the output files */
-    for (i = 0; i < nb_output_files; i++) {
-        os = output_files[i]->ctx;
-        if (os && os->oformat && !(os->oformat->flags & AVFMT_NOFILE)) {
-            if ((ret = avio_closep(&os->pb)) < 0) {
-                av_log(NULL, AV_LOG_ERROR, "Error closing file %s: %s\n", os->url, av_err2str(ret));
-                if (exit_on_error)
-                    exit_program(1);
-            }
-        }
-    }
-
     /* close each encoder */
     for (i = 0; i < nb_output_streams; i++) {
         ost = output_streams[i];
diff --git a/fftools/ffmpeg_mux.c b/fftools/ffmpeg_mux.c
index 396e91184b..78395bebb4 100644
--- a/fftools/ffmpeg_mux.c
+++ b/fftools/ffmpeg_mux.c
@@ -35,6 +35,7 @@
 struct Muxer {
     /* filesize limit expressed in bytes */
     int64_t limit_filesize;
+    int64_t final_filesize;
     int header_written;
 };
 
@@ -304,6 +305,17 @@ int of_write_trailer(OutputFile *of)
         return ret;
     }
 
+    of->mux->final_filesize = of_filesize(of);
+
+    if (!(of->format->flags & AVFMT_NOFILE)) {
+        ret = avio_closep(&of->ctx->pb);
+        if (ret < 0) {
+            av_log(NULL, AV_LOG_ERROR, "Error closing file %s: %s\n",
+                   of->ctx->url, av_err2str(ret));
+            return ret;
+        }
+    }
+
     return 0;
 }
 
@@ -360,7 +372,9 @@ int64_t of_filesize(OutputFile *of)
     AVIOContext *pb = of->ctx->pb;
     int64_t ret = -1;
 
-    if (pb) {
+    if (of->mux->final_filesize)
+        ret = of->mux->final_filesize;
+    else if (pb) {
         ret = avio_size(pb);
         if (ret <= 0) // FIXME improve avio_size() so it works with non seekable output too
             ret = avio_tell(pb);