diff --git a/package.json b/package.json
index 6469ce855..54748508f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@modelcontextprotocol/sdk",
-  "version": "0.1.0",
+  "version": "0.1.1",
   "description": "Model Context Protocol implementation for TypeScript",
   "type": "module",
   "main": "./dist/index.js",
diff --git a/src/shared/protocol.ts b/src/shared/protocol.ts
index 417f79da8..fdb117ca2 100644
--- a/src/shared/protocol.ts
+++ b/src/shared/protocol.ts
@@ -180,8 +180,8 @@ export class Protocol<
             jsonrpc: "2.0",
             id: request.id,
             error: {
-              code: error["code"]
-                ? Math.floor(Number(error["code"]))
+              code: Number.isSafeInteger(error["code"])
+                ? error["code"]
                 : ErrorCode.InternalError,
               message: error.message ?? "Internal error",
             },