diff --git a/libavformat/asfenc.c b/libavformat/asfenc.c
index d03cff91c0b48..8eaa9d40ce421 100644
--- a/libavformat/asfenc.c
+++ b/libavformat/asfenc.c
@@ -1130,7 +1130,6 @@ static int asf_write_trailer(AVFormatContext *s)
             return ret;
         asf_write_index(s, asf->index_ptr, asf->maximum_packet, asf->next_start_sec);
     }
-    avio_flush(s->pb);
 
     if (asf->is_streamed || !(s->pb->seekable & AVIO_SEEKABLE_NORMAL)) {
         put_chunk(s, 0x4524, 0, 0); /* end of stream */
diff --git a/libavformat/avienc.c b/libavformat/avienc.c
index 23cc58ea76ccc..d6cfb1b783929 100644
--- a/libavformat/avienc.c
+++ b/libavformat/avienc.c
@@ -591,7 +591,6 @@ static void update_odml_entry(AVFormatContext *s, int stream_index, int64_t ix,
     int64_t pos;
     int au_byterate, au_ssize, au_scale;
 
-    avio_flush(pb);
     pos = avio_tell(pb);
 
     /* Updating one entry in the AVI OpenDML master index */
diff --git a/libavformat/gxfenc.c b/libavformat/gxfenc.c
index c9fb0dcd91bd0..e09b8d76256cd 100644
--- a/libavformat/gxfenc.c
+++ b/libavformat/gxfenc.c
@@ -863,13 +863,11 @@ static int gxf_write_trailer(AVFormatContext *s)
         return ret;
     gxf_write_flt_packet(s);
     gxf_write_umf_packet(s);
-    avio_flush(pb);
     /* update duration in all map packets */
     for (i = 1; i < gxf->map_offsets_nb; i++) {
         avio_seek(pb, gxf->map_offsets[i], SEEK_SET);
         if ((ret = gxf_write_map_packet(s, 1)) < 0)
             return ret;
-        avio_flush(pb);
     }
 
     avio_seek(pb, end, SEEK_SET);
diff --git a/libavformat/segafilmenc.c b/libavformat/segafilmenc.c
index f1048ff8082a2..812d0ad64e947 100644
--- a/libavformat/segafilmenc.c
+++ b/libavformat/segafilmenc.c
@@ -362,8 +362,6 @@ static int film_write_header(AVFormatContext *format_context)
 
     avio_wb32(pb, film->packet_count);
 
-    avio_flush(pb);
-
     /* Finally, write out each packet's data to the header */
     packet = film->start;
     while (packet != NULL) {
diff --git a/libavformat/wavenc.c b/libavformat/wavenc.c
index ea7573139cb63..f6f5710802d1c 100644
--- a/libavformat/wavenc.c
+++ b/libavformat/wavenc.c
@@ -411,17 +411,13 @@ static int wav_write_trailer(AVFormatContext *s)
     int rf64 = 0;
     int ret = 0;
 
-    avio_flush(pb);
-
     if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
         if (wav->write_peak != PEAK_ONLY && avio_tell(pb) - wav->data < UINT32_MAX) {
             ff_end_tag(pb, wav->data);
-            avio_flush(pb);
         }
 
         if (wav->write_peak && wav->peak_output) {
             ret = peak_write_chunk(s);
-            avio_flush(pb);
         }
 
         /* update file size */
@@ -433,8 +429,6 @@ static int wav_write_trailer(AVFormatContext *s)
             avio_seek(pb, 4, SEEK_SET);
             avio_wl32(pb, (uint32_t)(file_size - 8));
             avio_seek(pb, file_size, SEEK_SET);
-
-            avio_flush(pb);
         } else {
             av_log(s, AV_LOG_ERROR,
                    "Filesize %"PRId64" invalid for wav, output file will be broken\n",
@@ -454,7 +448,6 @@ static int wav_write_trailer(AVFormatContext *s)
             } else {
                 avio_wl32(pb, number_of_samples);
                 avio_seek(pb, file_size, SEEK_SET);
-                avio_flush(pb);
             }
         }