diff --git a/libbsv/src/core/mod.rs b/libbsv/src/core/mod.rs
index a8ba778..f18c214 100644
--- a/libbsv/src/core/mod.rs
+++ b/libbsv/src/core/mod.rs
@@ -17,6 +17,7 @@
 pub mod error;
 pub mod config;
 pub mod object_id;
+pub mod object;
 pub mod repository;
 
 
@@ -27,4 +28,5 @@ pub const VERSION: &'static str = env!("CARGO_PKG_VERSION");
 pub use error::{Error, Result, ErrorKind};
 pub use config::{Config, RepositoryConfig};
 pub use object_id::ObjectId;
+pub use object::{ObjectType, OTYPE_BLOB, OTYPE_TREE};
 pub use repository::Repository;
diff --git a/libbsv/src/core/object.rs b/libbsv/src/core/object.rs
new file mode 100644
index 0000000..bee86d8
--- /dev/null
+++ b/libbsv/src/core/object.rs
@@ -0,0 +1,20 @@
+// This file is part of bsv.
+//
+// bsv is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// cdb is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
+// more details.
+//
+// You should have received a copy of the Affero GNU General Public License
+// along with cdb.  If not, see <https://www.gnu.org/licenses/>.
+
+
+pub type ObjectType = [u8; 4];
+
+pub const OTYPE_BLOB: &ObjectType = b"blob";
+pub const OTYPE_TREE: &ObjectType = b"tree";
diff --git a/libbsv/src/lib.rs b/libbsv/src/lib.rs
index 1d49bd4..9baed7d 100644
--- a/libbsv/src/lib.rs
+++ b/libbsv/src/lib.rs
@@ -25,6 +25,8 @@ pub mod simple_db;
 pub use crate::core::{
     Error, Result, ErrorKind,
     Config, RepositoryConfig,
-    ObjectId,
+    ObjectId, ObjectType,
     Repository,
+
+    OTYPE_BLOB, OTYPE_TREE,
 };
diff --git a/libbsv/src/simple_db/mod.rs b/libbsv/src/simple_db/mod.rs
index 1e0f8f0..e20b18c 100644
--- a/libbsv/src/simple_db/mod.rs
+++ b/libbsv/src/simple_db/mod.rs
@@ -20,6 +20,5 @@ pub mod object;
 
 pub use simple_db::SimpleDb;
 pub use object::{
-    OTYPE_BLOB, OTYPE_TREE,
     ObjectReader,
 };
diff --git a/libbsv/src/simple_db/object.rs b/libbsv/src/simple_db/object.rs
index f1323e8..8f8c2c0 100644
--- a/libbsv/src/simple_db/object.rs
+++ b/libbsv/src/simple_db/object.rs
@@ -30,12 +30,7 @@ use flate2::{
 
 use crate::core::error::*;
 use crate::core::ObjectId;
-
-
-pub type ObjectType = [u8; 4];
-
-pub const OTYPE_BLOB: &ObjectType = b"blob";
-pub const OTYPE_TREE: &ObjectType = b"tree";
+use crate::core::ObjectType;
 
 
 pub struct ObjectWriter<W: Write, D: Digest> {
@@ -190,6 +185,8 @@ impl<T: Read + Seek> WriteAsObject for T {
 
 #[cfg(test)]
 mod tests {
+    use crate::core::OTYPE_BLOB;
+
     use super::*;
 
     const PAYLOAD: &[u8; 12] = b"Hello World!";
diff --git a/libbsv/src/simple_db/simple_db.rs b/libbsv/src/simple_db/simple_db.rs
index d973558..21ad913 100644
--- a/libbsv/src/simple_db/simple_db.rs
+++ b/libbsv/src/simple_db/simple_db.rs
@@ -24,10 +24,10 @@ use tempfile::{NamedTempFile};
 
 use crate::core::error::*;
 use crate::core::ObjectId;
+use crate::core::{ObjectType, OTYPE_BLOB};
 
 use super::object::{
-    OTYPE_BLOB,
-    ObjectReader, ObjectType, WriteAsObject,
+    ObjectReader, WriteAsObject,
 };
 
 
diff --git a/libbsv/tests/simple_db.rs b/libbsv/tests/simple_db.rs
index 03aa2c0..a5236a0 100644
--- a/libbsv/tests/simple_db.rs
+++ b/libbsv/tests/simple_db.rs
@@ -27,8 +27,8 @@ use tempfile::{TempDir};
 use libbsv::{
     Result,
     ObjectId,
+    OTYPE_BLOB,
     simple_db::{
-        OTYPE_BLOB,
         SimpleDb,
     }
 };