diff --git a/subprojects/gst-plugins-good/gst/isomp4/gstqtmuxmap.c b/subprojects/gst-plugins-good/gst/isomp4/gstqtmuxmap.c
index 143b217431..18dbe93392 100644
--- a/subprojects/gst-plugins-good/gst/isomp4/gstqtmuxmap.c
+++ b/subprojects/gst-plugins-good/gst/isomp4/gstqtmuxmap.c
@@ -205,7 +205,8 @@ GstQTMuxFormatProp gst_qt_mux_format_list[] = {
             COMMON_VIDEO_CAPS "; "
             "video/x-dirac, "
             COMMON_VIDEO_CAPS "; " "video/x-qt-part, " COMMON_VIDEO_CAPS "; "
-            "video/x-av1, " COMMON_VIDEO_CAPS),
+            "video/x-av1, " "alignment = (string) \"tu\", "
+            COMMON_VIDEO_CAPS ";"),
         GST_STATIC_CAPS (PCM_CAPS_FULL "; "
             PCM_CAPS_UNPOSITIONED " ; "
             MP123_CAPS " ; "
@@ -229,7 +230,8 @@ GstQTMuxFormatProp gst_qt_mux_format_list[] = {
         GST_STATIC_CAPS ("video/quicktime, variant = (string) iso"),
         GST_STATIC_CAPS (MPEG4V_CAPS "; " H264_CAPS ";" H265_CAPS ";"
             "video/x-mp4-part," COMMON_VIDEO_CAPS "; "
-            "video/x-av1, " COMMON_VIDEO_CAPS),
+            "video/x-av1, " "alignment = (string) \"tu\", "
+            COMMON_VIDEO_CAPS ";"),
         GST_STATIC_CAPS (MP123_CAPS "; "
             AAC_CAPS " ; " AC3_CAPS " ; " ALAC_CAPS " ; " OPUS_CAPS),
         GST_STATIC_CAPS (TEXT_UTF8),
diff --git a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
index 8bc9df7a7d..091864b1f8 100644
--- a/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
+++ b/subprojects/gst-plugins-good/gst/isomp4/qtdemux.c
@@ -14749,7 +14749,8 @@ qtdemux_video_caps (GstQTDemux * qtdemux, QtDemuxStream * stream,
       break;
     case FOURCC_av01:
       _codec ("AV1");
-      caps = gst_caps_new_empty_simple ("video/x-av1");
+      caps = gst_caps_new_simple ("video/x-av1",
+          "alignment", G_TYPE_STRING, "tu", NULL);
       break;
     case GST_MAKE_FOURCC ('k', 'p', 'c', 'd'):
     default: