diff --git a/Cargo.lock b/Cargo.lock
index c8150b9e..920455ef 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -318,7 +318,7 @@ dependencies = [
 
 [[package]]
 name = "shardtree"
-version = "0.2.0"
+version = "0.3.0"
 dependencies = [
  "assert_matches",
  "bitflags 2.4.1",
diff --git a/shardtree/CHANGELOG.md b/shardtree/CHANGELOG.md
index fc8e49a6..8f4c6a01 100644
--- a/shardtree/CHANGELOG.md
+++ b/shardtree/CHANGELOG.md
@@ -7,17 +7,22 @@ and this project adheres to Rust's notion of
 
 ## Unreleased
 
-## Added
+## [0.3.0] - 2024-03-25
+
+### Added
 - `ShardTree::{store, store_mut}`
 - `ShardTree::insert_frontier`
 
+### Changed
+- `shardtree::error::InsertionError` has new variant `MarkedRetentionInvalid`
+
 ## [0.2.0] - 2023-11-07
 
-## Added
+### Added
 - `ShardTree::{root_at_checkpoint_id, root_at_checkpoint_id_caching}`
 - `ShardTree::{witness_at_checkpoint_id, witness_at_checkpoint_id_caching}`
 
-## Changed
+### Changed
 - `ShardTree::root_at_checkpoint` and `ShardTree::root_at_checkpoint_caching` have
   been renamed to `root_at_checkpoint_depth` and `root_at_checkpoint_depth_caching`,
   respectively.
diff --git a/shardtree/Cargo.toml b/shardtree/Cargo.toml
index 0a8baefb..49005b26 100644
--- a/shardtree/Cargo.toml
+++ b/shardtree/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "shardtree"
-version = "0.2.0"
+version = "0.3.0"
 authors = [
     "Kris Nuttycombe <kris@nutty.land>",
 ]
diff --git a/shardtree/src/error.rs b/shardtree/src/error.rs
index df6e9658..2debfb71 100644
--- a/shardtree/src/error.rs
+++ b/shardtree/src/error.rs
@@ -80,8 +80,7 @@ pub enum InsertionError {
     InputMalformed(Address),
     // The caller attempted to mark the empty tree state as corresponding to the state
     // for a spendable note.
-    // TODO: Add this proper error type for `shardtree-0.3.0`
-    //MarkedRetentionInvalid,
+    MarkedRetentionInvalid,
 }
 
 impl fmt::Display for InsertionError {
@@ -108,9 +107,10 @@ impl fmt::Display for InsertionError {
             InsertionError::TreeFull => write!(f, "Note commitment tree is full."),
             InsertionError::InputMalformed(addr) => {
                 write!(f, "Input malformed for insertion at address {:?}", addr)
-            } //InsertionError::MarkedRetentionInvalid => {
-              //    write!(f, "Cannot use `Marked` retention for the empty tree.")
-              //}
+            }
+            InsertionError::MarkedRetentionInvalid => {
+                write!(f, "Cannot use `Marked` retention for the empty tree.")
+            }
         }
     }
 }
diff --git a/shardtree/src/lib.rs b/shardtree/src/lib.rs
index 1e7073bf..1f4510af 100644
--- a/shardtree/src/lib.rs
+++ b/shardtree/src/lib.rs
@@ -292,8 +292,7 @@ impl<
                     is_marked: true, ..
                 }
                 | Retention::Marked => Err(ShardTreeError::Insert(
-                    //TODO: use InsertionError::MarkedRetentionInvalid for `shardtree-0.3.0`
-                    InsertionError::CheckpointOutOfOrder,
+                    InsertionError::MarkedRetentionInvalid,
                 )),
             }
         }