diff --git a/libmpdemux/demux_bmp.c b/libmpdemux/demux_bmp.c
index 093c2ffa04..7ec2e6c973 100644
--- a/libmpdemux/demux_bmp.c
+++ b/libmpdemux/demux_bmp.c
@@ -23,9 +23,6 @@ typedef struct {
 // Check if a file is a BMP file depending on whether starts with 'BM'
 int bmp_check_file(demuxer_t *demuxer)
 {
-  stream_reset(demuxer->stream);
-  stream_seek(demuxer->stream, 0);
-
   if (stream_read_word(demuxer->stream) == (('B' << 8) | 'M'))
     return 1;
   else
diff --git a/libmpdemux/demux_rawdv.c b/libmpdemux/demux_rawdv.c
index ac25015fe1..34cc3c8c61 100644
--- a/libmpdemux/demux_rawdv.c
+++ b/libmpdemux/demux_rawdv.c
@@ -68,8 +68,6 @@ int rawdv_check_file(demuxer_t *demuxer)
 
    mp_msg(MSGT_DEMUX,MSGL_V,"Checking for DV\n");
 
-   stream_reset(demuxer->stream);
-   stream_seek(demuxer->stream, 0);
    bytes_read=stream_read(demuxer->stream,tmp_buffer,DV_PAL_FRAME_SIZE);
    if ((bytes_read!=DV_PAL_FRAME_SIZE) && (bytes_read!=DV_NTSC_FRAME_SIZE))
       return 0;
diff --git a/libmpdemux/demux_roq.c b/libmpdemux/demux_roq.c
index 9cfbd0d71b..cb28520f89 100644
--- a/libmpdemux/demux_roq.c
+++ b/libmpdemux/demux_roq.c
@@ -50,9 +50,6 @@ typedef struct roq_data_t
 //  84 10 FF FF FF FF xx xx
 int roq_check_file(demuxer_t *demuxer)
 {
-  stream_reset(demuxer->stream);
-  stream_seek(demuxer->stream, 0);
-
   if ((stream_read_dword(demuxer->stream) == 0x8410FFFF) &&
       ((stream_read_dword(demuxer->stream) & 0xFFFF0000) == 0xFFFF0000))
     return 1;