diff --git a/schemata/config-v1.json b/schemata/config-v1.json
index a73d6cf..68eff9f 100644
--- a/schemata/config-v1.json
+++ b/schemata/config-v1.json
@@ -24,6 +24,12 @@
 					"title": "Host",
 					"type": "string"
 				},
+				"music_directory": {
+					"description": "Your music directory, just as it's set up in your mpd.conf. mpd-now-playable uses this setting to figure out an absolute file:// URL for the current song, which MPNowPlayingInfoCenter will use to display cool stuff like audio waveforms. It'll still work fine without setting this, though.",
+					"format": "directory-path",
+					"title": "Music Directory",
+					"type": "string"
+				},
 				"password": {
 					"description": "The password required to connect to your MPD instance, if you need one.",
 					"format": "password",
diff --git a/schemata/song-v1.json b/schemata/song-v1.json
index a16bda4..6ecc4ec 100644
--- a/schemata/song-v1.json
+++ b/schemata/song-v1.json
@@ -194,6 +194,12 @@
 			"description": "The track number the song has on its album. This is usually one-based, but it's just an arbitrary audio tag so a particular album might start at zero or do something weird with it.",
 			"title": "Track",
 			"type": "integer"
+		},
+		"url": {
+			"description": "An absolute URL referring to the current song, if available. If the song's a local file and its absolute path can be determined (mpd-now-playable has been configured with your music directory), then this field will contain a file:// URL. If the song's remote, then MPD itself returns an absolute URL in the first place.",
+			"format": "uri",
+			"title": "Url",
+			"type": "string"
 		}
 	},
 	"required": [
diff --git a/src/mpd_now_playable/config/model.py b/src/mpd_now_playable/config/model.py
index 561d830..0fde2d1 100644
--- a/src/mpd_now_playable/config/model.py
+++ b/src/mpd_now_playable/config/model.py
@@ -4,7 +4,7 @@ from typing import Annotated, Literal, Optional, Protocol
 from pydantic import Field
 
 from ..tools.schema.define import schema
-from .fields import Host, Password, Port, Url
+from ..tools.schema.fields import DirectoryPath, Host, Password, Port, Url
 
 __all__ = (
 	"Config",
@@ -55,6 +55,12 @@ class MpdConfig:
 	#: servers on one machine for some reason, you probably haven't changed this
 	#: from the default port, 6600.
 	port: Port = Port(6600)
+	#: Your music directory, just as it's set up in your mpd.conf.
+	#: mpd-now-playable uses this setting to figure out an absolute file:// URL
+	#: for the current song, which MPNowPlayingInfoCenter will use to display
+	#: cool stuff like audio waveforms. It'll still work fine without setting
+	#: this, though.
+	music_directory: Optional[DirectoryPath] = None
 
 
 @schema("https://cdn.00dani.me/m/schemata/mpd-now-playable/config-v1.json")
diff --git a/src/mpd_now_playable/mpd/listener.py b/src/mpd_now_playable/mpd/listener.py
index 1743bbb..75852f7 100644
--- a/src/mpd_now_playable/mpd/listener.py
+++ b/src/mpd_now_playable/mpd/listener.py
@@ -9,37 +9,55 @@ from yarl import URL
 
 from ..config.model import MpdConfig
 from ..player import Player
-from ..song import Artwork, PlaybackState, Song, to_artwork, to_brainz
+from ..song import PlaybackState, Song, to_artwork, to_brainz
 from ..song_receiver import Receiver
 from ..tools.types import option_fmap, un_maybe_plural
 from .artwork_cache import MpdArtworkCache
-from .types import CurrentSongResponse, StatusResponse
+from .types import MpdState
 
 
-def mpd_current_to_song(
-	status: StatusResponse, current: CurrentSongResponse, art: Artwork
-) -> Song:
+def mpd_file_to_uri(config: MpdConfig, file: str) -> URL | None:
+	url = URL(file)
+	if url.scheme != "":
+		# We already got an absolute URL - probably a stream? - so we can just return it.
+		return url
+
+	if not config.music_directory:
+		# We have a relative song URI, but we can't make it absolute since no music directory is configured.
+		return None
+
+	# Prepend the configured music directory, then turn the whole path into a file:// URL.
+	abs_file = config.music_directory / file
+	return URL(abs_file.as_uri())
+
+
+def mpd_state_to_song(config: MpdConfig, mpd: MpdState) -> Song:
+	file = mpd.current["file"]
+	url = mpd_file_to_uri(config, file)
+
 	return Song(
-		state=PlaybackState(status["state"]),
-		queue_index=int(current["pos"]),
-		queue_length=int(status["playlistlength"]),
-		file=Path(current["file"]),
-		title=current.get("title"),
-		artist=un_maybe_plural(current.get("artist")),
-		album=un_maybe_plural(current.get("album")),
-		album_artist=un_maybe_plural(current.get("albumartist")),
-		composer=un_maybe_plural(current.get("composer")),
-		genre=un_maybe_plural(current.get("genre")),
-		track=option_fmap(int, current.get("track")),
-		disc=option_fmap(int, current.get("disc")),
-		duration=float(status["duration"]),
-		elapsed=float(status["elapsed"]),
-		musicbrainz=to_brainz(current),
-		art=art,
+		state=PlaybackState(mpd.status["state"]),
+		queue_index=int(mpd.current["pos"]),
+		queue_length=int(mpd.status["playlistlength"]),
+		file=Path(file),
+		url=url,
+		title=mpd.current.get("title"),
+		artist=un_maybe_plural(mpd.current.get("artist")),
+		album=un_maybe_plural(mpd.current.get("album")),
+		album_artist=un_maybe_plural(mpd.current.get("albumartist")),
+		composer=un_maybe_plural(mpd.current.get("composer")),
+		genre=un_maybe_plural(mpd.current.get("genre")),
+		track=option_fmap(int, mpd.current.get("track")),
+		disc=option_fmap(int, mpd.current.get("disc")),
+		duration=option_fmap(float, mpd.status.get("duration")),
+		elapsed=float(mpd.status["elapsed"]),
+		musicbrainz=to_brainz(mpd.current),
+		art=to_artwork(mpd.art),
 	)
 
 
 class MpdStateListener(Player):
+	config: MpdConfig
 	client: MPDClient
 	receivers: Iterable[Receiver]
 	art_cache: MpdArtworkCache
@@ -52,6 +70,7 @@ class MpdStateListener(Player):
 		)
 
 	async def start(self, conf: MpdConfig) -> None:
+		self.config = conf
 		print(f"Connecting to MPD server {conf.host}:{conf.port}...")
 		await self.client.connect(conf.host, conf.port)
 		if conf.password is not None:
@@ -77,6 +96,7 @@ class MpdStateListener(Player):
 		status, current = await asyncio.gather(
 			self.client.status(), self.client.currentsong()
 		)
+		state = MpdState(status, current)
 
 		if starting_idle_count != self.idle_count:
 			return
@@ -90,7 +110,8 @@ class MpdStateListener(Player):
 		if starting_idle_count != self.idle_count:
 			return
 
-		song = mpd_current_to_song(status, current, to_artwork(art))
+		state = MpdState(status, current, art)
+		song = mpd_state_to_song(self.config, state)
 		rprint(song)
 		await self.update(song)
 
diff --git a/src/mpd_now_playable/mpd/types.py b/src/mpd_now_playable/mpd/types.py
index 4183e5d..8d9db81 100644
--- a/src/mpd_now_playable/mpd/types.py
+++ b/src/mpd_now_playable/mpd/types.py
@@ -1,3 +1,4 @@
+from dataclasses import dataclass
 from typing import Literal, NotRequired, Protocol, TypedDict
 
 from ..song.musicbrainz import MusicBrainzTags
@@ -19,8 +20,11 @@ OneshotFlag = Literal[BooleanFlag, "oneshot"]
 class StatusResponse(TypedDict):
 	state: Literal["play", "stop", "pause"]
 
-	# The total duration and elapsed playback of the current song, measured in seconds. Fractional seconds are allowed.
-	duration: str
+	# The total duration and elapsed playback of the current song, measured in
+	# seconds. Fractional seconds are allowed. The duration field may be
+	# omitted because MPD cannot determine the duration of certain sources,
+	# such as Internet radio streams.
+	duration: NotRequired[str]
 	elapsed: str
 
 	# The volume value ranges from 0-100. It may be omitted from
@@ -76,3 +80,10 @@ class CurrentSongResponse(CurrentSongTags):
 
 
 ReadPictureResponse = TypedDict("ReadPictureResponse", {"binary": bytes})
+
+
+@dataclass
+class MpdState:
+	status: StatusResponse
+	current: CurrentSongResponse
+	art: bytes | None = None
diff --git a/src/mpd_now_playable/receivers/cocoa/now_playing.py b/src/mpd_now_playable/receivers/cocoa/now_playing.py
index d207b65..c67c733 100644
--- a/src/mpd_now_playable/receivers/cocoa/now_playing.py
+++ b/src/mpd_now_playable/receivers/cocoa/now_playing.py
@@ -25,6 +25,7 @@ from MediaPlayer import (
 	MPNowPlayingInfoCenter,
 	MPNowPlayingInfoMediaTypeAudio,
 	MPNowPlayingInfoMediaTypeNone,
+	MPNowPlayingInfoPropertyAssetURL,
 	MPNowPlayingInfoPropertyElapsedPlaybackTime,
 	MPNowPlayingInfoPropertyExternalContentIdentifier,
 	MPNowPlayingInfoPropertyMediaType,
@@ -106,6 +107,9 @@ def song_to_media_item(song: Song) -> NSMutableDictionary:
 	nowplaying_info[MPMediaItemPropertyComposer] = join_plural_field(song.composer)
 	nowplaying_info[MPMediaItemPropertyPlaybackDuration] = song.duration
 
+	if song.url is not None:
+		nowplaying_info[MPNowPlayingInfoPropertyAssetURL] = song.url.human_repr()
+
 	# MPD can't play back music at different rates, so we just want to set it
 	# to 1.0 if the song is playing. (Leave it at 0.0 if the song is paused.)
 	if song.state == PlaybackState.play:
diff --git a/src/mpd_now_playable/receivers/websockets/receiver.py b/src/mpd_now_playable/receivers/websockets/receiver.py
index 22c35bb..5cbce3d 100644
--- a/src/mpd_now_playable/receivers/websockets/receiver.py
+++ b/src/mpd_now_playable/receivers/websockets/receiver.py
@@ -3,6 +3,7 @@ from pathlib import Path
 import ormsgpack
 from websockets import broadcast
 from websockets.server import WebSocketServerProtocol, serve
+from yarl import URL
 
 from ...config.model import WebsocketsReceiverConfig
 from ...player import Player
@@ -15,6 +16,8 @@ MSGPACK_NULL = ormsgpack.packb(None)
 def default(value: object) -> object:
 	if isinstance(value, Path):
 		return str(value)
+	if isinstance(value, URL):
+		return value.human_repr()
 	raise TypeError
 
 
diff --git a/src/mpd_now_playable/song/song.py b/src/mpd_now_playable/song/song.py
index 716dff0..45c4425 100644
--- a/src/mpd_now_playable/song/song.py
+++ b/src/mpd_now_playable/song/song.py
@@ -3,6 +3,7 @@ from enum import StrEnum
 from pathlib import Path
 
 from ..tools.schema.define import schema
+from ..tools.schema.fields import Url
 from .artwork import Artwork
 from .musicbrainz import MusicBrainzIds
 
@@ -14,7 +15,7 @@ class PlaybackState(StrEnum):
 
 
 @schema("https://cdn.00dani.me/m/schemata/mpd-now-playable/song-v1.json")
-@dataclass(slots=True)
+@dataclass(slots=True, kw_only=True)
 class Song:
 	#: Whether MPD is currently playing, paused, or stopped. Pretty simple.
 	state: PlaybackState
@@ -30,6 +31,13 @@ class Song:
 	#: places, so you can safely do the same.
 	file: Path
 
+	#: An absolute URL referring to the current song, if available. If the
+	#: song's a local file and its absolute path can be determined
+	#: (mpd-now-playable has been configured with your music directory), then
+	#: this field will contain a file:// URL. If the song's remote, then MPD
+	#: itself returns an absolute URL in the first place.
+	url: Url | None = None
+
 	#: The song's title, if it's been tagged with one. Currently only one title
 	#: is supported, since it doesn't make a lot of sense to tag a single audio
 	#: file with multiple titles.
@@ -61,8 +69,9 @@ class Song:
 	genre: list[str]
 
 	#: The song's duration as read from its tags, measured in seconds.
-	#: Fractional seconds are allowed.
-	duration: float
+	#: Fractional seconds are allowed. The duration may be unavailable for some
+	#: sources, such as internet radio streams.
+	duration: float | None
 
 	#: How far into the song MPD is, measured in seconds. Fractional seconds
 	#: are allowed. This is usually going to be less than or equal to the
diff --git a/src/mpd_now_playable/config/fields.py b/src/mpd_now_playable/tools/schema/fields.py
similarity index 77%
rename from src/mpd_now_playable/config/fields.py
rename to src/mpd_now_playable/tools/schema/fields.py
index f73a7f9..f171e28 100644
--- a/src/mpd_now_playable/config/fields.py
+++ b/src/mpd_now_playable/tools/schema/fields.py
@@ -1,7 +1,9 @@
+from os.path import expanduser
 from typing import Annotated, NewType
 
 from annotated_types import Ge, Le
 from pydantic import (
+	BeforeValidator,
 	Field,
 	PlainSerializer,
 	PlainValidator,
@@ -9,9 +11,12 @@ from pydantic import (
 	Strict,
 	WithJsonSchema,
 )
+from pydantic import (
+	DirectoryPath as DirectoryType,
+)
 from yarl import URL as Yarl
 
-__all__ = ("Host", "Password", "Port", "Url")
+__all__ = ("DirectoryPath", "Host", "Password", "Port", "Url")
 
 
 def from_yarl(url: Yarl) -> str:
@@ -24,6 +29,7 @@ def to_yarl(value: object) -> Yarl:
 	raise NotImplementedError(f"Cannot convert {type(object)} to URL")
 
 
+DirectoryPath = Annotated[DirectoryType, BeforeValidator(expanduser)]
 Host = NewType(
 	"Host", Annotated[str, Strict(), Field(json_schema_extra={"format": "hostname"})]
 )
diff --git a/src/mpd_now_playable/tools/schema/generate.py b/src/mpd_now_playable/tools/schema/generate.py
index ec1b539..a8d71ef 100644
--- a/src/mpd_now_playable/tools/schema/generate.py
+++ b/src/mpd_now_playable/tools/schema/generate.py
@@ -11,8 +11,8 @@ from .define import ModelWithSchema
 __all__ = ("write",)
 
 
-def write(model: ModelWithSchema) -> None:
-	schema = model.schema.json_schema(schema_generator=MyGenerateJsonSchema)
+def write(model: ModelWithSchema, mode: JsonSchemaMode = "validation") -> None:
+	schema = model.schema.json_schema(schema_generator=MyGenerateJsonSchema, mode=mode)
 	schema["$id"] = model.id.human_repr()
 	schema_file = Path(__file__).parents[4] / "schemata" / model.id.name
 	print(f"Writing this schema to {schema_file}")
@@ -46,8 +46,10 @@ class MyGenerateJsonSchema(GenerateJsonSchema):
 	def nullable_schema(self, schema: s.NullableSchema) -> JsonSchemaValue:
 		return self.generate_inner(schema["schema"])
 
-if __name__ == '__main__':
+
+if __name__ == "__main__":
 	from ...config.model import Config
 	from ...song import Song
+
 	write(Config)
-	write(Song)
+	write(Song, mode="serialization")
diff --git a/stubs/MediaPlayer/__init__.pyi b/stubs/MediaPlayer/__init__.pyi
index 01682fe..86c1226 100644
--- a/stubs/MediaPlayer/__init__.pyi
+++ b/stubs/MediaPlayer/__init__.pyi
@@ -34,6 +34,7 @@ MPNowPlayingInfoPropertyPlaybackQueueIndex: Final = (
 MPNowPlayingInfoPropertyElapsedPlaybackTime: Final = (
 	"MPNowPlayingInfoPropertyElapsedPlaybackTime"
 )
+MPNowPlayingInfoPropertyAssetURL: Final = "MPNowPlayingInfoPropertyAssetURL"
 MPNowPlayingInfoPropertyExternalContentIdentifier: Final = (
 	"MPNowPlayingInfoPropertyExternalContentIdentifier"
 )