diff --git a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
index bf6bbf6659..ee01e280af 100644
--- a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
+++ b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
@@ -12176,7 +12176,7 @@ qtdemux_parse_trak (GstQTDemux * qtdemux, GNode * trak)
             guint16 primaries = GST_READ_UINT16_BE (colr_data + 12);
             guint16 transfer_function = GST_READ_UINT16_BE (colr_data + 14);
             guint16 matrix = GST_READ_UINT16_BE (colr_data + 16);
-            gboolean full_range = len == 19 ? colr_data[17] >> 7 : FALSE;
+            gboolean full_range = len == 19 ? colr_data[18] >> 7 : FALSE;
 
             CUR_STREAM (stream)->colorimetry.primaries =
                 gst_video_color_primaries_from_iso (primaries);