diff --git a/package.json b/package.json
index a1609ee1..c47f2fd7 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@automerge/automerge-repo-monorepo",
-  "version": "2.0.0-alpha.16",
+  "version": "2.0.0-alpha.17",
   "description": "Automerge Repo monorepo",
   "main": "packages/automerge-repo/dist/index.js",
   "repository": "https://github.com/automerge/automerge-repo",
diff --git a/packages/automerge-repo/src/types.ts b/packages/automerge-repo/src/types.ts
index 12b84ca9..aa605204 100644
--- a/packages/automerge-repo/src/types.ts
+++ b/packages/automerge-repo/src/types.ts
@@ -27,8 +27,11 @@ export type AnyDocumentId =
   | BinaryDocumentId
   | LegacyDocumentId
 
+// We need to define our own version of heads because the AutomergeHeads type is not bs58check encoded
+export type UrlHeads = string[] & { __automergeUrlHeads: unknown }
+
 /** A branded type for peer IDs */
 export type PeerId = string & { __peerId: true }
 
 /** A randomly generated string created when the {@link Repo} starts up */
-export type SessionId = string & { __SessionId: true }
+export type SessionId = string & { __sessionId: true }