diff --git a/src/collection/album.rs b/src/core/collection/album.rs
similarity index 100%
rename from src/collection/album.rs
rename to src/core/collection/album.rs
diff --git a/src/collection/artist.rs b/src/core/collection/artist.rs
similarity index 100%
rename from src/collection/artist.rs
rename to src/core/collection/artist.rs
diff --git a/src/collection/merge.rs b/src/core/collection/merge.rs
similarity index 100%
rename from src/collection/merge.rs
rename to src/core/collection/merge.rs
diff --git a/src/collection/mod.rs b/src/core/collection/mod.rs
similarity index 100%
rename from src/collection/mod.rs
rename to src/core/collection/mod.rs
diff --git a/src/collection/track.rs b/src/core/collection/track.rs
similarity index 100%
rename from src/collection/track.rs
rename to src/core/collection/track.rs
diff --git a/src/database/json/backend.rs b/src/core/database/json/backend.rs
similarity index 100%
rename from src/database/json/backend.rs
rename to src/core/database/json/backend.rs
diff --git a/src/database/json/mod.rs b/src/core/database/json/mod.rs
similarity index 97%
rename from src/database/json/mod.rs
rename to src/core/database/json/mod.rs
index 9dff3c8..873dd37 100644
--- a/src/database/json/mod.rs
+++ b/src/core/database/json/mod.rs
@@ -66,7 +66,7 @@ mod tests {
 
     use mockall::predicate;
 
-    use crate::{musichoard::testmod::FULL_COLLECTION, Artist, ArtistId, Collection};
+    use crate::{core::musichoard::testmod::FULL_COLLECTION, Artist, ArtistId, Collection};
 
     use super::*;
     use testmod::DATABASE_JSON;
diff --git a/src/database/json/testmod.rs b/src/core/database/json/testmod.rs
similarity index 100%
rename from src/database/json/testmod.rs
rename to src/core/database/json/testmod.rs
diff --git a/src/database/mod.rs b/src/core/database/mod.rs
similarity index 100%
rename from src/database/mod.rs
rename to src/core/database/mod.rs
diff --git a/src/library/beets/executor.rs b/src/core/library/beets/executor.rs
similarity index 100%
rename from src/library/beets/executor.rs
rename to src/core/library/beets/executor.rs
diff --git a/src/library/beets/mod.rs b/src/core/library/beets/mod.rs
similarity index 99%
rename from src/library/beets/mod.rs
rename to src/core/library/beets/mod.rs
index 0c6cee1..29fd719 100644
--- a/src/library/beets/mod.rs
+++ b/src/core/library/beets/mod.rs
@@ -4,7 +4,7 @@
 #[cfg(test)]
 use mockall::automock;
 
-use crate::collection::track::Format;
+use crate::core::collection::track::Format;
 
 use super::{Error, Field, ILibrary, Item, Query};
 
diff --git a/src/library/beets/testmod.rs b/src/core/library/beets/testmod.rs
similarity index 100%
rename from src/library/beets/testmod.rs
rename to src/core/library/beets/testmod.rs
diff --git a/src/library/mod.rs b/src/core/library/mod.rs
similarity index 99%
rename from src/library/mod.rs
rename to src/core/library/mod.rs
index 645081a..1ac85f2 100644
--- a/src/library/mod.rs
+++ b/src/core/library/mod.rs
@@ -5,7 +5,7 @@ use std::{collections::HashSet, fmt, num::ParseIntError, str::Utf8Error};
 #[cfg(test)]
 use mockall::automock;
 
-use crate::collection::track::Format;
+use crate::core::collection::track::Format;
 
 #[cfg(feature = "library-beets")]
 pub mod beets;
diff --git a/src/library/testmod.rs b/src/core/library/testmod.rs
similarity index 99%
rename from src/library/testmod.rs
rename to src/core/library/testmod.rs
index 638aeb2..87b5dc2 100644
--- a/src/library/testmod.rs
+++ b/src/core/library/testmod.rs
@@ -1,6 +1,6 @@
 use once_cell::sync::Lazy;
 
-use crate::{collection::track::Format, library::Item};
+use crate::{library::Item, Format};
 
 pub static LIBRARY_ITEMS: Lazy<Vec<Item>> = Lazy::new(|| -> Vec<Item> {
     vec![
diff --git a/src/core/mod.rs b/src/core/mod.rs
new file mode 100644
index 0000000..870545f
--- /dev/null
+++ b/src/core/mod.rs
@@ -0,0 +1,4 @@
+pub mod collection;
+pub mod database;
+pub mod library;
+pub mod musichoard;
diff --git a/src/musichoard/mod.rs b/src/core/musichoard/mod.rs
similarity index 100%
rename from src/musichoard/mod.rs
rename to src/core/musichoard/mod.rs
diff --git a/src/musichoard/testmod.rs b/src/core/musichoard/testmod.rs
similarity index 92%
rename from src/musichoard/testmod.rs
rename to src/core/musichoard/testmod.rs
index 6df9f36..d2a55ac 100644
--- a/src/musichoard/testmod.rs
+++ b/src/core/musichoard/testmod.rs
@@ -1,4 +1,4 @@
-use crate::collection::{
+use crate::core::collection::{
     album::{Album, AlbumId},
     artist::{Artist, ArtistId, ArtistProperties, Bandcamp, MusicBrainz, MusicButler, Qobuz},
     track::{Format, Quality, Track, TrackId},
diff --git a/src/musichoard/tests.rs b/src/core/musichoard/tests.rs
similarity index 99%
rename from src/musichoard/tests.rs
rename to src/core/musichoard/tests.rs
index c9a646c..adc07c4 100644
--- a/src/musichoard/tests.rs
+++ b/src/core/musichoard/tests.rs
@@ -5,7 +5,7 @@ use super::*;
 use super::testmod::{FULL_COLLECTION, LIBRARY_COLLECTION};
 
 // FIXME: check all crate::* imports - are the tests where they should be?
-use crate::collection::{
+use crate::core::collection::{
     artist::{ArtistProperties, Bandcamp, MusicBrainz, MusicButler, Qobuz},
     track::Format,
     Merge,
diff --git a/src/lib.rs b/src/lib.rs
index c1d1906..b5103bb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,26 +1,27 @@
 //! MusicHoard - a music collection manager.
 
-mod collection;
-mod musichoard;
-
-// FIXME: make private and fix via re-exports.
-pub mod database;
-pub mod library;
+// FIXME: make private and only provide via re-exports.
+pub mod core;
 
 use std::fmt::{self, Display};
 
-use collection::artist::InvalidUrlError;
+// FIXME: validate the re-exports.
+pub use core::database;
+pub use core::library;
 
 // FIXME: validate the re-exports.
-pub use collection::{
+pub use core::collection::{
     album::{Album, AlbumId},
-    artist::{Artist, ArtistId, ArtistProperties, Bandcamp, MusicBrainz, MusicButler, Qobuz},
+    artist::{
+        Artist, ArtistId, ArtistProperties, Bandcamp, InvalidUrlError, MusicBrainz, MusicButler,
+        Qobuz,
+    },
     track::{Format, Quality, Track, TrackId},
     Collection,
 };
 
 // FIXME: validate the re-exports
-pub use musichoard::{MusicHoard, MusicHoardBuilder, NoDatabase, NoLibrary};
+pub use core::musichoard::{MusicHoard, MusicHoardBuilder, NoDatabase, NoLibrary};
 
 // FIXME: this should be in the musichoard module.
 /// Error type for `musichoard`.