diff --git a/api/funkwhale_api/federation/serializers.py b/api/funkwhale_api/federation/serializers.py
index 4330fb33c..99e47df5d 100644
--- a/api/funkwhale_api/federation/serializers.py
+++ b/api/funkwhale_api/federation/serializers.py
@@ -1,5 +1,6 @@
 import logging
 import os
+import re
 import urllib.parse
 import uuid
 
@@ -1580,6 +1581,50 @@ class TrackSerializer(MusicEntitySerializer):
         return super().update(obj, validated_data)
 
 
+def duration_int_to_xml(duration):
+    if not duration:
+        return None
+
+    multipliers = {"S": 1, "M": 60, "H": 3600, "D": 86400}
+    ret = "P"
+    days, seconds = divmod(int(duration), multipliers["D"])
+    ret += f"{days:d}DT" if days > 0 else "T"
+    hours, seconds = divmod(seconds, multipliers["H"])
+    ret += f"{hours:d}H" if hours > 0 else ""
+    minutes, seconds = divmod(seconds, multipliers["M"])
+    ret += f"{minutes:d}M" if minutes > 0 else ""
+    ret += f"{seconds:d}S" if seconds > 0 or ret == "PT" else ""
+    return ret
+
+
+class DayTimeDurationSerializer(serializers.DurationField):
+    multipliers = {"S": 1, "M": 60, "H": 3600, "D": 86400}
+
+    def to_internal_value(self, value):
+        if isinstance(value, float):
+            return value
+
+        parsed = re.match(
+            r"P([0-9]+D)?T([0-9]+H)?([0-9]+M)?([0-9]+(?:\.[0-9]+)?S)?", str(value)
+        )
+        if parsed is not None:
+            return int(
+                sum(
+                    [
+                        self.multipliers[s[-1]] * float("0" + s[:-1])
+                        for s in parsed.groups()
+                        if s is not None
+                    ]
+                )
+            )
+        self.fail(
+            "invalid", format="https://www.w3.org/TR/xmlschema11-2/#dayTimeDuration"
+        )
+
+    def to_representation(self, value):
+        duration_int_to_xml(value)
+
+
 class UploadSerializer(jsonld.JsonLdSerializer):
     type = serializers.ChoiceField(choices=[contexts.AS.Audio])
     id = serializers.URLField(max_length=500)
@@ -1589,7 +1634,7 @@ class UploadSerializer(jsonld.JsonLdSerializer):
     updated = serializers.DateTimeField(required=False, allow_null=True)
     bitrate = serializers.IntegerField(min_value=0)
     size = serializers.IntegerField(min_value=0)
-    duration = serializers.IntegerField(min_value=0)
+    duration = DayTimeDurationSerializer(min_value=0)
 
     track = TrackSerializer(required=True)
 
@@ -1701,7 +1746,7 @@ class UploadSerializer(jsonld.JsonLdSerializer):
             "published": instance.creation_date.isoformat(),
             "bitrate": instance.bitrate,
             "size": instance.size,
-            "duration": instance.duration,
+            "duration": duration_int_to_xml(instance.duration),
             "url": [
                 {
                     "href": utils.full_url(instance.listen_url_no_download),
@@ -1851,7 +1896,7 @@ class ChannelUploadSerializer(jsonld.JsonLdSerializer):
     url = LinkListSerializer(keep_mediatype=["audio/*"], min_length=1)
     name = serializers.CharField()
     published = serializers.DateTimeField(required=False)
-    duration = serializers.IntegerField(min_value=0, required=False)
+    duration = DayTimeDurationSerializer(required=False)
     position = serializers.IntegerField(min_value=0, allow_null=True, required=False)
     disc = serializers.IntegerField(min_value=1, allow_null=True, required=False)
     album = serializers.URLField(max_length=500, required=False)
@@ -1960,7 +2005,7 @@ class ChannelUploadSerializer(jsonld.JsonLdSerializer):
         if upload.track.local_license:
             data["license"] = upload.track.local_license["identifiers"][0]
 
-        include_if_not_none(data, upload.duration, "duration")
+        include_if_not_none(data, duration_int_to_xml(upload.duration), "duration")
         include_if_not_none(data, upload.track.position, "position")
         include_if_not_none(data, upload.track.disc_number, "disc")
         include_if_not_none(data, upload.track.copyright, "copyright")
diff --git a/api/funkwhale_api/music/models.py b/api/funkwhale_api/music/models.py
index 9fc7e9e72..fe1e2b0c9 100644
--- a/api/funkwhale_api/music/models.py
+++ b/api/funkwhale_api/music/models.py
@@ -719,7 +719,7 @@ class Track(APIModelMixin):
     @property
     def listen_url(self) -> str:
         # Not using reverse because this is slow
-        return f"/api/v1/listen/{self.uuid}/"
+        return f"/api/v2/listen/{self.uuid}/"
 
     @property
     def local_license(self):
diff --git a/api/tests/federation/test_serializers.py b/api/tests/federation/test_serializers.py
index d764e29b3..37883ca5c 100644
--- a/api/tests/federation/test_serializers.py
+++ b/api/tests/federation/test_serializers.py
@@ -1268,7 +1268,7 @@ def test_activity_pub_upload_serializer_from_ap(factories, mocker, r_mock):
         "name": "Ignored",
         "published": published.isoformat(),
         "updated": updated.isoformat(),
-        "duration": 43,
+        "duration": "PT43S",
         "bitrate": 42,
         "size": 66,
         "url": {"href": "https://audio.file", "type": "Link", "mediaType": "audio/mp3"},
@@ -1337,7 +1337,7 @@ def test_activity_pub_upload_serializer_from_ap(factories, mocker, r_mock):
     assert track_create.call_count == 1
     assert upload.fid == data["id"]
     assert upload.track.fid == data["track"]["id"]
-    assert upload.duration == data["duration"]
+    assert upload.duration == 43
     assert upload.size == data["size"]
     assert upload.bitrate == data["bitrate"]
     assert upload.source == data["url"]["href"]
@@ -1357,7 +1357,7 @@ def test_activity_pub_upload_serializer_from_ap_update(factories, mocker, now, r
         "name": "Ignored",
         "published": now.isoformat(),
         "updated": now.isoformat(),
-        "duration": 42,
+        "duration": "PT42S",
         "bitrate": 42,
         "size": 66,
         "url": {
@@ -1376,7 +1376,7 @@ def test_activity_pub_upload_serializer_from_ap_update(factories, mocker, now, r
     upload.refresh_from_db()
 
     assert upload.fid == data["id"]
-    assert upload.duration == data["duration"]
+    assert upload.duration == 42
     assert upload.size == data["size"]
     assert upload.bitrate == data["bitrate"]
     assert upload.source == data["url"]["href"]
@@ -1408,7 +1408,7 @@ def test_activity_pub_audio_serializer_to_ap(factories):
         "name": upload.track.full_name,
         "published": upload.creation_date.isoformat(),
         "updated": upload.modification_date.isoformat(),
-        "duration": upload.duration,
+        "duration": "PT43S",
         "bitrate": upload.bitrate,
         "size": upload.size,
         "to": contexts.AS.Public,
@@ -1777,7 +1777,7 @@ def test_channel_upload_serializer(factories):
         "content": common_utils.render_html(content.text, content.content_type),
         "to": "https://www.w3.org/ns/activitystreams#Public",
         "position": upload.track.position,
-        "duration": upload.duration,
+        "duration": "PT54S",
         "album": upload.track.album.fid,
         "disc": upload.track.disc_number,
         "copyright": upload.track.copyright,
@@ -1826,7 +1826,7 @@ def test_channel_upload_serializer_from_ap_create(factories, now, mocker):
         "published": now.isoformat(),
         "mediaType": "text/html",
         "content": "<p>Hello</p>",
-        "duration": 543,
+        "duration": "PT543S",
         "position": 4,
         "disc": 2,
         "album": album.fid,
@@ -1875,7 +1875,7 @@ def test_channel_upload_serializer_from_ap_create(factories, now, mocker):
     assert upload.mimetype == payload["url"][1]["mediaType"]
     assert upload.size == payload["url"][1]["size"]
     assert upload.bitrate == payload["url"][1]["bitrate"]
-    assert upload.duration == payload["duration"]
+    assert upload.duration == 543
     assert upload.track.artist_credit.all()[0].artist == channel.artist
     assert upload.track.position == payload["position"]
     assert upload.track.disc_number == payload["disc"]
@@ -1909,7 +1909,7 @@ def test_channel_upload_serializer_from_ap_update(factories, now, mocker):
         "published": now.isoformat(),
         "mediaType": "text/html",
         "content": "<p>Hello</p>",
-        "duration": 543,
+        "duration": "PT543S",
         "position": 4,
         "disc": 2,
         "album": album.fid,
@@ -1959,7 +1959,7 @@ def test_channel_upload_serializer_from_ap_update(factories, now, mocker):
     assert upload.mimetype == payload["url"][1]["mediaType"]
     assert upload.size == payload["url"][1]["size"]
     assert upload.bitrate == payload["url"][1]["bitrate"]
-    assert upload.duration == payload["duration"]
+    assert upload.duration == 543
     assert upload.track.artist_credit.all()[0].artist == channel.artist
     assert upload.track.position == payload["position"]
     assert upload.track.disc_number == payload["disc"]
diff --git a/changes/changelog.d/1566.bugfix b/changes/changelog.d/1566.bugfix
new file mode 100644
index 000000000..be6a67fcf
--- /dev/null
+++ b/changes/changelog.d/1566.bugfix
@@ -0,0 +1 @@
+ActivityStreams compliance: duration (#1566)
diff --git a/docs/developer/federation/index.md b/docs/developer/federation/index.md
index 38619c31f..59fd7bc51 100644
--- a/docs/developer/federation/index.md
+++ b/docs/developer/federation/index.md
@@ -798,8 +798,7 @@ An `Audio` object is a custom object used to store upload information. It extend
     - Integer
     - The bitrate of the audio in bytes/s
   * - `duration`*
-    - Integer
-    - The duration of the audio in seconds
+    - The duration of the audio as defined in [as](https://www.w3.org/TR/activitystreams-vocabulary/#dfn-duration)
   * - `library`*
     - String (URI)
     - The ID of the audio's containing [`Library` object](#library)
@@ -826,7 +825,7 @@ An `Audio` object is a custom object used to store upload information. It extend
   "name": "Krav Boca - Mortem",
   "size": 8656581,
   "bitrate": 320000,
-  "duration": 213,
+  "duration": "PT1312S,
   "library": "https://awesome.music/federation/music/libraries/dc702491-f6ce-441b-9da0-cecbed08bcc6",
   "updated": "2018-10-02T19:49:35.646372+00:00",
   "published": "2018-10-02T19:49:35.646359+00:00",