diff --git a/libavformat/isom.h b/libavformat/isom.h
index 4154baf827..220b2df4e1 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -110,7 +110,7 @@ typedef struct MOVStreamContext {
     int ctts_index;
     int ctts_sample;
     unsigned int sample_size; ///< may contain value calculated from stsd or value from stsz atom
-    unsigned int alt_sample_size; ///< always contains sample size from stsz atom
+    unsigned int stsz_sample_size; ///< always contains sample size from stsz atom
     unsigned int sample_count;
     int *sample_sizes;
     int keyframe_absent;
diff --git a/libavformat/mov.c b/libavformat/mov.c
index d5e1f893f5..7048920e75 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -1721,7 +1721,7 @@ static int mov_read_stsz(MOVContext *c, AVIOContext *pb, MOVAtom atom)
         sample_size = avio_rb32(pb);
         if (!sc->sample_size) /* do not overwrite value computed in stsd */
             sc->sample_size = sample_size;
-        sc->alt_sample_size = sample_size;
+        sc->stsz_sample_size = sample_size;
         field_size = 32;
     } else {
         sample_size = 0;
@@ -2018,7 +2018,7 @@ static void mov_build_index(MOVContext *mov, AVStream *st)
                 }
                 if (keyframe)
                     distance = 0;
-                sample_size = sc->alt_sample_size > 0 ? sc->alt_sample_size : sc->sample_sizes[current_sample];
+                sample_size = sc->stsz_sample_size > 0 ? sc->stsz_sample_size : sc->sample_sizes[current_sample];
                 if (sc->pseudo_stream_id == -1 ||
                    sc->stsc_data[stsc_index].id - 1 == sc->pseudo_stream_id) {
                     AVIndexEntry *e = &st->index_entries[st->nb_index_entries++];