diff --git a/packages/opentelemetry-context-zone-peer-dep/README.md b/packages/opentelemetry-context-zone-peer-dep/README.md
index 119e054846..e068b8ec54 100644
--- a/packages/opentelemetry-context-zone-peer-dep/README.md
+++ b/packages/opentelemetry-context-zone-peer-dep/README.md
@@ -12,6 +12,9 @@ If you don't have your own [zone-js] please use [@opentelemetry/context-zone]
 
 ## Installation
 
+Please note that due to an issue with `zone.js`, the `ZoneContextManager` does not work with JS code targeting `ES2017+`.
+In order to use the `ZoneContextManager`, please transpile back to `ES2015`.
+
 ```bash
 npm install --save @opentelemetry/context-zone-peer-dep
 ```
diff --git a/packages/opentelemetry-web/README.md b/packages/opentelemetry-web/README.md
index d7ea41b666..117d91e379 100644
--- a/packages/opentelemetry-web/README.md
+++ b/packages/opentelemetry-web/README.md
@@ -23,7 +23,7 @@ Web Tracer currently supports one plugin for document load.
 Unlike Node Tracer (`NodeTracerProvider`), the plugins needs to be initialised and passed in configuration.
 The reason is to give user full control over which plugin will be bundled into web page.
 
-You can choose to use the `ZoneContextManager` if you want to trace asynchronous operations.
+You can choose to use the `ZoneContextManager` if you want to trace asynchronous operations. Please note that the `ZoneContextManager` does not work with JS code targeting `ES2017+`. In order to use the `ZoneContextManager`, please transpile back to `ES2015`.
 
 ## Installation