diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index f878ced0fa..974edea462 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -3478,8 +3478,6 @@ static int mov_write_ftyp_tag(AVIOContext *pb, AVFormatContext *s)
         ffio_wfourcc(pb, "qt  ");
     else if (mov->mode == MODE_ISM) {
         ffio_wfourcc(pb, "piff");
-        if (!(mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF))
-            ffio_wfourcc(pb, "iso2");
     } else if (!(mov->flags & FF_MOV_FLAG_DEFAULT_BASE_MOOF)) {
         ffio_wfourcc(pb, "isom");
         ffio_wfourcc(pb, "iso2");
diff --git a/tests/ref/lavf/ismv b/tests/ref/lavf/ismv
index 2c8d92c292..ab2975f0bf 100644
--- a/tests/ref/lavf/ismv
+++ b/tests/ref/lavf/ismv
@@ -1,9 +1,9 @@
-17b0b8eff852edd25fa38aed062689d7 *./tests/data/lavf/lavf.ismv
-312546 ./tests/data/lavf/lavf.ismv
+b1106bfcdbd1bb12be9161320351dd00 *./tests/data/lavf/lavf.ismv
+312542 ./tests/data/lavf/lavf.ismv
 ./tests/data/lavf/lavf.ismv CRC=0xb7d29d29
-543e5146df7bd4b7eb7edc94e0034ad9 *./tests/data/lavf/lavf.ismv
-321452 ./tests/data/lavf/lavf.ismv
+c8bea6c84b6274f14042381045b0f532 *./tests/data/lavf/lavf.ismv
+321448 ./tests/data/lavf/lavf.ismv
 ./tests/data/lavf/lavf.ismv CRC=0x33834815
-17b0b8eff852edd25fa38aed062689d7 *./tests/data/lavf/lavf.ismv
-312546 ./tests/data/lavf/lavf.ismv
+b1106bfcdbd1bb12be9161320351dd00 *./tests/data/lavf/lavf.ismv
+312542 ./tests/data/lavf/lavf.ismv
 ./tests/data/lavf/lavf.ismv CRC=0xb7d29d29