diff --git a/.changeset/funny-beans-exist.md b/.changeset/funny-beans-exist.md
new file mode 100644
index 00000000..f0e193a8
--- /dev/null
+++ b/.changeset/funny-beans-exist.md
@@ -0,0 +1,5 @@
+---
+'@cloudflare/sandbox': patch
+---
+
+Fix `options` parameter types for `gitCheckout`
diff --git a/packages/sandbox/src/sandbox.ts b/packages/sandbox/src/sandbox.ts
index ad4b3932..baa81882 100644
--- a/packages/sandbox/src/sandbox.ts
+++ b/packages/sandbox/src/sandbox.ts
@@ -1868,12 +1868,12 @@ export class Sandbox<Env = unknown> extends Container<Env> implements ISandbox {
 
   async gitCheckout(
     repoUrl: string,
-    options: { branch?: string; targetDir?: string; sessionId?: string }
+    options?: { branch?: string; targetDir?: string; sessionId?: string }
   ) {
-    const session = options.sessionId ?? (await this.ensureDefaultSession());
+    const session = options?.sessionId ?? (await this.ensureDefaultSession());
     return this.client.git.checkout(repoUrl, session, {
-      branch: options.branch,
-      targetDir: options.targetDir
+      branch: options?.branch,
+      targetDir: options?.targetDir
     });
   }