diff --git a/modules/demux/mp4/mp4.c b/modules/demux/mp4/mp4.c
index dbdd65f0df..c6ddd68d2d 100644
--- a/modules/demux/mp4/mp4.c
+++ b/modules/demux/mp4/mp4.c
@@ -3577,9 +3577,10 @@ static int TrackTimeToSampleChunk( demux_t *p_demux, mp4_track_t *p_track,
     }
     else
     {
+        uint32_t i_group_sample_entry;
         const MP4_Box_data_sgpd_entry_t *p_entrydesc;
         if( MP4_SampleToGroupInfo( p_track->p_stbl, i_sample,
-                                  SAMPLEGROUP_roll, 0, &i_sync_sample,
+                                  SAMPLEGROUP_roll, 0, &i_group_sample_entry,
                                   SAMPLE_GROUP_MATCH_EXACT, &p_entrydesc ) )
         {
             msg_Dbg(p_demux, "track[Id 0x%x] preroll offset: %"PRId16" samples",