diff --git a/README.md b/README.md
index 0cbb979a..f45a723a 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,10 @@ It can read from:
 npm install strtok3
 ```
 
+### Compatibility
+
+NPM module is compliant with [ECMAScript 2018 (ES9)](https://en.wikipedia.org/wiki/ECMAScript#9th_Edition_%E2%80%93_ECMAScript_2018).
+
 ## API
 
 Use one of the methods to instantiate an [*abstract tokenizer*](#tokenizer):
diff --git a/tsconfig.json b/tsconfig.json
index 227c9643..133d2a8c 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -3,7 +3,7 @@
     "inlineSources": false,
     "module": "commonjs",
     "moduleResolution": "node",
-    "target": "ES2017",
+    "target": "ES2018",
     "strict": true
   }
 }