diff --git a/CHANGELOG.md b/CHANGELOG.md
index f031e2f0..bdd799c5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # This is the revision history of @msgpack/msgpack
 
+## NEXT
+
+* Revert use of `tslib` (added in 2.5.0) to fix [#169](https://github.com/msgpack/msgpack-javascript/issues/169)
+
 ## v2.5.1 2021/03/21
 
 https://github.com/msgpack/msgpack-javascript/compare/v2.5.0...v2.5.1
diff --git a/package.json b/package.json
index 00dd56cc..d5c6ff54 100644
--- a/package.json
+++ b/package.json
@@ -52,7 +52,6 @@
     "node": ">= 10"
   },
   "dependencies": {
-    "tslib": ">=2.0.0"
   },
   "devDependencies": {
     "@bitjourney/check-es-version-webpack-plugin": "latest",
diff --git a/tsconfig.json b/tsconfig.json
index 4ea9de15..b217e2bd 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -18,7 +18,7 @@
     // "tsBuildInfoFile": "./",               /* Specify file to store incremental compilation information */
     // "removeComments": true,                /* Do not emit comments to output. */
     // "noEmit": true,                        /* Do not emit outputs. */
-    "importHelpers": true,                 /* Import emit helpers from 'tslib'. */
+    "importHelpers": false,                 /* Import emit helpers from 'tslib'. */
     // "downlevelIteration": true,            /* Provide full support for iterables in 'for-of', spread, and destructuring when targeting 'ES5' or 'ES3'. */
     // "isolatedModules": true,               /* Transpile each file as a separate module (similar to 'ts.transpileModule'). */